diff --git a/InventoryApp.cs b/InventoryApp.cs
new file mode 100644
index 0000000..a6e8aa1
--- /dev/null
+++ b/InventoryApp.cs
@@ -0,0 +1,152 @@
+namespace InventoryManagementSystem
+{
+    public class InventoryApp
+    {
+        public static void Main(string[] args)
+        {
+            ProductManager manager = new ProductManager();
+
+            while (true)
+            {
+                Console.WriteLine("Inventory Management System");
+                Console.WriteLine("1. Add Product");
+                Console.WriteLine("2. Update Product");
+                Console.WriteLine("3. Delete Product");
+                Console.WriteLine("4. Display Inventory");
+                Console.WriteLine("5. Sale Product");
+                Console.WriteLine("6. Exit");
+                Console.WriteLine("Enter your choice:");
+
+                int choice;
+                if (!int.TryParse(Console.ReadLine(), out choice))
+                {
+                    Console.WriteLine("Invalid input. Please enter a number.");
+                    continue;
+                }
+
+                switch (choice)
+                {
+                    case 1:
+                        AddProduct(manager);
+                        break;
+                    case 2:
+                        UpdateProduct(manager);
+                        break;
+                    case 3:
+                        DeleteProduct(manager);
+                        break;
+                    case 4:
+                        manager.DisplayInventory();
+                        break;
+                    case 5:
+                        SellProduct(manager);
+                        break;
+                    case 6:
+                        Environment.Exit(0);
+                        break;
+                    default:
+                        Console.WriteLine("Invalid choice. Please enter a number between 1 and 5.");
+                        break;
+                }
+            }
+        }
+
+        private static void AddProduct(ProductManager manager)
+        {
+            try
+            {
+                Console.WriteLine("Enter product details:");
+                Console.Write("ID: ");
+                int id = int.Parse(Console.ReadLine());
+                Console.Write("Name: ");
+                string name = Console.ReadLine();
+                Console.Write("Price: ");
+                double price = double.Parse(Console.ReadLine());
+                Console.Write("Quantity: ");
+                int quantity = int.Parse(Console.ReadLine());
+
+                manager.AddProduct(new Product { Id = id, Name = name, Price = price, Quantity = quantity });
+            }
+            catch (FormatException)
+            {
+                Console.WriteLine("Invalid input format. Please enter valid data.");
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine($"Error: {ex.Message}");
+            }
+        }
+
+        private static void UpdateProduct(ProductManager manager)
+        {
+            try
+            {
+                Console.WriteLine("Enter product ID to update:");
+                int id = int.Parse(Console.ReadLine());
+                Console.WriteLine("Enter new product details:");
+                Console.Write("Name: ");
+                string name = Console.ReadLine();
+                Console.Write("Price: ");
+                double price = double.Parse(Console.ReadLine());
+                Console.Write("Quantity: ");
+                int quantity = int.Parse(Console.ReadLine());
+
+                manager.UpdateProduct(new Product { Id = id, Name = name, Price = price, Quantity = quantity });
+            }
+            catch (FormatException)
+            {
+                Console.WriteLine("Invalid input format. Please enter valid data.");
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine($"Error: {ex.Message}");
+            }
+        }
+
+        private static void DeleteProduct(ProductManager manager)
+        {
+            try
+            {
+                Console.WriteLine("Enter product ID to delete:");
+                int id = int.Parse(Console.ReadLine());
+                manager.DeleteProduct(id);
+            }
+            catch (FormatException)
+            {
+                Console.WriteLine("Invalid input format. Please enter valid data.");
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine($"Error: {ex.Message}");
+            }
+        }
+
+        private static void SellProduct(ProductManager manager)
+        {
+            try
+            {
+                Console.WriteLine("Enter Product ID:");
+                int id;
+                if (!int.TryParse(Console.ReadLine(), out id))
+                {
+                    Console.WriteLine("Invalid input for ID. Please enter a number.");
+                    return;
+                }
+
+                Console.WriteLine("Enter Quantity to Sell:");
+                int quantity;
+                if (!int.TryParse(Console.ReadLine(), out quantity) || quantity <= 0)
+                {
+                    Console.WriteLine("Invalid input for Quantity. Please enter a positive integer.");
+                    return;
+                }
+
+                manager.SellProduct(id, quantity);
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine($"Error: {ex.Message}");
+            }
+        }
+    }
+}
diff --git a/InventoryExceptions.cs b/InventoryExceptions.cs
new file mode 100644
index 0000000..fff2b4d
--- /dev/null
+++ b/InventoryExceptions.cs
@@ -0,0 +1,44 @@
+namespace InventoryManagementSystem
+{
+    public class DuplicateProductException : Exception
+    {
+        public DuplicateProductException(string message) : base(message)
+        {
+        }
+    }
+
+    public class InvalidPriceException : Exception
+    {
+        public InvalidPriceException(string message) : base(message)
+        {
+        }
+    }
+
+    public class InvalidInputDataException : Exception
+    {
+        public InvalidInputDataException(string message) : base(message)
+        {
+        }
+    }
+
+    public class OutOfStockException : Exception
+    {
+        public OutOfStockException(string message) : base(message)
+        {
+        }
+    }
+
+    public class ProductNotFoundException : Exception
+    {
+        public ProductNotFoundException(string message) : base(message)
+        {
+        }
+    }
+
+    public class InsufficientQuantityException : Exception
+    {
+        public InsufficientQuantityException(string message) : base(message)
+        {
+        }
+    }
+}
\ No newline at end of file
diff --git a/Product.cs b/Product.cs
new file mode 100644
index 0000000..05af972
--- /dev/null
+++ b/Product.cs
@@ -0,0 +1,10 @@
+namespace InventoryManagementSystem
+{
+    public class Product
+    {
+        public int Id { get; set; }
+        public string Name { get; set; }
+        public double Price { get; set; }
+        public int Quantity { get; set; }
+    }
+}
\ No newline at end of file
diff --git a/ProductManager.cs b/ProductManager.cs
new file mode 100644
index 0000000..1d6d0cc
--- /dev/null
+++ b/ProductManager.cs
@@ -0,0 +1,83 @@
+namespace InventoryManagementSystem
+{
+    public class ProductManager
+    {
+        private List<Product> inventory = new List<Product>();
+
+        public void AddProduct(Product product)
+        {
+            if (inventory.Exists(p => p.Id == product.Id))
+            {
+                throw new DuplicateProductException($"Product with ID {product.Id} already exists.");
+            }
+            if (product.Id < 0 || product.Price < 0 || product.Quantity < 0)
+            {
+                throw new InvalidInputDataException("Id, Price and quantity cannot be negative.");
+            }
+            if (product.Price == 0)
+            {
+                throw new InvalidPriceException("Product price cannot be zero.");
+            }
+
+            inventory.Add(product);
+            Console.WriteLine($"Product '{product.Name}' added successfully.");
+        }
+
+        public void UpdateProduct(Product product)
+        {
+            int index = inventory.FindIndex(p => p.Id == product.Id);
+            if (index == -1)
+            {
+                throw new ProductNotFoundException($"Product with ID {product.Id} not found.");
+            }
+            if (product.Id < 0 || product.Price < 0 || product.Quantity < 0)
+            {
+                throw new InvalidInputDataException("Id, Price and quantity cannot be negative.");
+            }
+
+            inventory[index] = product;
+            Console.WriteLine($"Product '{product.Name}' updated successfully.");
+        }
+
+        public void DeleteProduct(int productId)
+        {
+            int index = inventory.FindIndex(p => p.Id == productId);
+            if (index == -1)
+            {
+                throw new ProductNotFoundException($"Product with ID {productId} not found.");
+            }
+
+            inventory.RemoveAt(index);
+            Console.WriteLine($"Product with ID {productId} deleted successfully.");
+        }
+
+        public void SellProduct(int productId, int quantityToSell)
+        {
+            Product product = inventory.Find(p => p.Id == productId);
+            if (product == null)
+            {
+                throw new ProductNotFoundException($"Product with ID {productId} not found.");
+            }
+            if (product.Quantity < quantityToSell)
+            {
+                if (product.Quantity == 0)
+                {
+                    throw new OutOfStockException($"Product '{product.Name}' is currently out of stock.");
+                }
+                throw new InsufficientQuantityException($"Insufficient quantity of product '{product.Name}'. Available: {product.Quantity}");
+            }
+
+            product.Quantity -= quantityToSell;
+            Console.WriteLine($"Sold {quantityToSell} units of product '{product.Name}'.");
+        }
+
+        public void DisplayInventory()
+        {
+            Console.WriteLine("Inventory:");
+            foreach (var product in inventory)
+            {
+                Console.WriteLine($"ID: {product.Id}, Name: {product.Name}, Price: {product.Price}, Quantity: {product.Quantity}");
+            }
+        }
+    }
+}
\ No newline at end of file