diff --git a/.github/.keep b/.github/.keep
new file mode 100644
index 00000000..e69de29b
diff --git a/src/main/java/com/example/Category.java b/src/main/java/com/example/Category.java
new file mode 100644
index 00000000..6b9632f7
--- /dev/null
+++ b/src/main/java/com/example/Category.java
@@ -0,0 +1,30 @@
+package com.example;
+
+import java.util.HashMap;
+
+public class Category {
+    public String name;
+    static HashMap<String, Category> categories = new HashMap<>();
+
+    private Category(String categoryName) {
+        name = categoryName;
+        name = name.substring(0, 1).toUpperCase()
+                + name.substring(1).toLowerCase();
+    }
+
+    public static Category of(String name) {
+        if (name == null) {
+            throw new IllegalArgumentException("Category name can't be null");
+        } else if (name.isBlank())
+            throw new IllegalArgumentException("Category name can't be blank");
+        if (categories.containsKey(name))
+                return categories.get(name);
+        categories.put(name, new Category(name));
+        return categories.get(name);
+    }
+
+    public String getName() {
+        return name;
+    }
+}
+
diff --git a/src/main/java/com/example/ElectronicsProduct.java b/src/main/java/com/example/ElectronicsProduct.java
new file mode 100644
index 00000000..17d36747
--- /dev/null
+++ b/src/main/java/com/example/ElectronicsProduct.java
@@ -0,0 +1,40 @@
+package com.example;
+
+import java.math.BigDecimal;
+import java.util.UUID;
+
+public class ElectronicsProduct extends Product implements Shippable {
+    int warrantyMonths;
+    BigDecimal weight;
+    BigDecimal basePrice = BigDecimal.valueOf(79);
+    BigDecimal addPrice = BigDecimal.valueOf(49);
+
+    public ElectronicsProduct(UUID id, String name, Category category, BigDecimal price, int warranty, BigDecimal weight) {
+        super(id, name, category, price);
+        this.warrantyMonths = warranty;
+        if (warrantyMonths < 0)
+            throw new IllegalArgumentException("Warranty months cannot be negative.");
+        this.weight = weight;
+    }
+
+    public int getWarrantyMonths() {
+        return warrantyMonths;
+    }
+
+    @Override
+    public String productDetails() {
+        return "Electronics: " + name + ", Warranty: " + warrantyMonths + " months";
+    }
+
+    @Override
+    public double weight() {
+        return weight.doubleValue();
+    }
+
+    @Override
+    public BigDecimal calculateShippingCost() {
+        return (weight.compareTo(BigDecimal.valueOf(5.0)) >= 0)
+            ? basePrice.add(addPrice)
+            : basePrice;
+    }
+}
diff --git a/src/main/java/com/example/FoodProduct.java b/src/main/java/com/example/FoodProduct.java
new file mode 100644
index 00000000..c50b8f3a
--- /dev/null
+++ b/src/main/java/com/example/FoodProduct.java
@@ -0,0 +1,38 @@
+package com.example;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+import java.util.UUID;
+
+public class FoodProduct extends Product implements Perishable, Shippable {
+    public LocalDate expirationDate;
+    public BigDecimal weight;
+
+    public FoodProduct(UUID id, String name, Category category, BigDecimal price, LocalDate expirationDate, BigDecimal weight) {
+        super(id, name, category, price);
+        this.expirationDate = expirationDate;
+        if (weight.compareTo(BigDecimal.ZERO) < 0)
+            throw new IllegalArgumentException("Weight cannot be negative.");
+        this.weight = weight;
+    }
+
+    @Override
+    public LocalDate expirationDate() {
+        return expirationDate;
+    }
+
+    @Override
+    public String productDetails() {
+        return "Food: " + name + ", Expires: " + expirationDate;
+    }
+
+    @Override
+    public double weight() {
+        return weight.doubleValue();
+    }
+
+    @Override
+    public BigDecimal calculateShippingCost() {
+        return weight.multiply(BigDecimal.valueOf(50));
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/example/Perishable.java b/src/main/java/com/example/Perishable.java
new file mode 100644
index 00000000..adeba099
--- /dev/null
+++ b/src/main/java/com/example/Perishable.java
@@ -0,0 +1,10 @@
+package com.example;
+
+import java.time.LocalDate;
+
+interface Perishable {
+    LocalDate expirationDate();
+    default boolean isExpired() {
+        return LocalDate.now().isAfter(expirationDate());
+    }
+}
diff --git a/src/main/java/com/example/Product.java b/src/main/java/com/example/Product.java
new file mode 100644
index 00000000..ba422d27
--- /dev/null
+++ b/src/main/java/com/example/Product.java
@@ -0,0 +1,42 @@
+package com.example;
+
+import java.math.BigDecimal;
+import java.util.UUID;
+
+public abstract class Product {
+    UUID uuid;
+    String name;
+    Category category;
+    BigDecimal price;
+
+    public Product(UUID uuid, String name, Category category, BigDecimal price) {
+        this.uuid = uuid;
+        this.name = name;
+        this.category = category;
+        if(price.compareTo(BigDecimal.ZERO) < 0)
+            throw new IllegalArgumentException("Price cannot be negative.");
+        this.price = price;
+    }
+
+    public BigDecimal price() {
+        return price;
+    }
+
+    public void setPrice(BigDecimal price) {
+        this.price = price;
+    }
+
+    public UUID uuid() {
+        return uuid;
+    }
+
+    public String name() {
+        return name;
+    }
+
+    public Category category() {
+        return category;
+    }
+
+    public abstract String productDetails();
+}
diff --git a/src/main/java/com/example/Shippable.java b/src/main/java/com/example/Shippable.java
new file mode 100644
index 00000000..6b1b2e49
--- /dev/null
+++ b/src/main/java/com/example/Shippable.java
@@ -0,0 +1,8 @@
+package com.example;
+
+import java.math.BigDecimal;
+
+public interface Shippable {
+    BigDecimal calculateShippingCost();
+    double weight();
+}
diff --git a/src/main/java/com/example/Warehouse.java b/src/main/java/com/example/Warehouse.java
new file mode 100644
index 00000000..33e6a417
--- /dev/null
+++ b/src/main/java/com/example/Warehouse.java
@@ -0,0 +1,114 @@
+package com.example;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.*;
+
+public class Warehouse {
+    static HashMap<String, Warehouse> warehouses = new HashMap<>();
+    HashMap<UUID, Product> products;
+    List<Shippable> shippables;
+    List<Perishable> perishables;
+    HashMap<Optional<Product>, HashMap<LocalDateTime, BigDecimal>> changedProducts;
+
+    private Warehouse() {
+        this.products = new HashMap<>();
+        this.shippables = new ArrayList<>();
+        this.perishables = new ArrayList<>();
+        this.changedProducts = new HashMap<>();
+    }
+
+    public List<Product> getProducts(){
+        return List.copyOf(products.values());
+    }
+
+    public List<Shippable> shippableProducts() {
+        return shippables;
+    }
+
+    public void clearProducts(){
+        products.clear();
+        Category.categories.clear();
+        shippables.clear();
+        perishables.clear();
+    }
+
+    public boolean isEmpty(){
+        return products.isEmpty();
+    }
+
+    public void addProduct(Product product){
+        if (product == null)
+            throw new IllegalArgumentException("Product cannot be null.");
+        if (getProductById(product.uuid).isPresent())
+            throw new IllegalArgumentException("Product with that id already exists, use updateProduct for updates.");
+        products.put(product.uuid, product);
+        if(product instanceof Shippable)
+            shippables.add((Shippable) product);
+        if(product instanceof Perishable)
+            perishables.add((Perishable) product);
+    }
+
+    public void remove(UUID id){
+        products.remove(id);
+    }
+
+    public Optional<Product> getProductById(UUID id){
+       if (products.isEmpty())
+           return Optional.empty();
+        return (Optional.ofNullable(products.get(id)));
+    }
+
+    public static synchronized Warehouse getInstance(String string) {
+        if (!warehouses.containsKey(string)) {
+            warehouses.put(string, new Warehouse());
+        }
+        return warehouses.get(string);
+    }
+
+    public static synchronized Warehouse getInstance() {
+        if(!warehouses.containsKey("default"))
+            warehouses.put("default", new  Warehouse());
+        return warehouses.get("default");
+    }
+
+    public Map<Category, List<Product>> getProductsGroupedByCategories() {
+        if(products == null || products.isEmpty()){
+            return Collections.emptyMap();
+        }
+        HashMap<Category, List<Product>> result = new HashMap<>();
+        var tempMap = Category.categories.entrySet();
+        var productsList = new ArrayList<>(products.values());
+        for(var category : tempMap){
+            List<Product> tempList = new ArrayList<>();
+            productsList.stream()
+                    .filter(element -> element.category.equals(category.getValue()))
+                    .forEach(tempList::add);
+            result.put(category.getValue(), tempList);
+        }
+        return result;
+    }
+
+    public void updateProductPrice(UUID id, BigDecimal newPrice){
+        var product = getProductById(id);
+        if(product.isPresent()) {
+            var tempMap = new HashMap<LocalDateTime, BigDecimal>();
+            tempMap.put(LocalDateTime.now(), product.get().price);
+            changedProducts.put(product, tempMap);
+            product.get().setPrice(newPrice);
+        }
+        else
+            throw new NoSuchElementException("Product not found with id:" + id);
+    }
+
+    public Map<Optional<Product>, HashMap<LocalDateTime, BigDecimal>> getChangedProducts(){
+            return changedProducts;
+    }
+
+    public List<Perishable> expiredProducts() {
+        return perishables.stream()
+                .filter(Perishable::isExpired)
+                .toList();
+    }
+}
+
diff --git a/src/main/java/com/example/WarehouseAnalyzer.java b/src/main/java/com/example/WarehouseAnalyzer.java
index 1779fc33..54349ac5 100644
--- a/src/main/java/com/example/WarehouseAnalyzer.java
+++ b/src/main/java/com/example/WarehouseAnalyzer.java
@@ -145,26 +145,46 @@ public Map<Category, BigDecimal> calculateWeightedAveragePriceByCategory() {
      * @param standardDeviations threshold in standard deviations (e.g., 2.0)
      * @return list of products considered outliers
      */
+
+
     public List<Product> findPriceOutliers(double standardDeviations) {
-        List<Product> products = warehouse.getProducts();
-        int n = products.size();
-        if (n == 0) return List.of();
-        double sum = products.stream().map(Product::price).mapToDouble(bd -> bd.doubleValue()).sum();
-        double mean = sum / n;
-        double variance = products.stream()
+        List<Product> productList = warehouse.getProducts();
+        List<BigDecimal> products = productList.stream()
                 .map(Product::price)
-                .mapToDouble(bd -> Math.pow(bd.doubleValue() - mean, 2))
-                .sum() / n;
-        double std = Math.sqrt(variance);
-        double threshold = standardDeviations * std;
+                .sorted()
+                .toList();
+
+        var Q1 = getPercentile(products, 25);
+        var Q3 = getPercentile(products, 75);
+
+        var IQR = Q3.doubleValue()-Q1.doubleValue();
+        var lowRange = Q1.doubleValue()-standardDeviations*IQR;
+        var highRange = Q3.doubleValue()+standardDeviations*IQR;
+
         List<Product> outliers = new ArrayList<>();
-        for (Product p : products) {
-            double diff = Math.abs(p.price().doubleValue() - mean);
-            if (diff > threshold) outliers.add(p);
+        for(Product p : productList){
+            if((p.price.doubleValue()>highRange) || (p.price.doubleValue()<lowRange))
+                outliers.add(p);
         }
         return outliers;
     }
-    
+
+
+    static <T extends Comparable<T>> T getPercentile(Collection<T> input, double percentile) {
+        if (input == null || input.isEmpty()) {
+            throw new IllegalArgumentException("The input dataset cannot be null or empty.");
+        }
+        if (percentile < 0 || percentile > 100) {
+            throw new IllegalArgumentException("Percentile must be between 0 and 100 inclusive.");
+        }
+        List<T> sortedList = input.stream()
+                .sorted()
+                .collect(Collectors.toList());
+
+        int rank = percentile == 0 ? 1 : (int) Math.ceil(percentile / 100.0 * input.size());
+        return sortedList.get(rank - 1);
+    }
+
     /**
      * Groups all shippable products into ShippingGroup buckets such that each group's total weight
      * does not exceed the provided maximum. The goal is to minimize the number of groups and/or total