using System;

​

class BankAccount

{

    private string _accountHolder;

    private decimal _balance;

​

    public BankAccount(string name) => (_accountHolder, _balance) = (name, 0);

​

    public void Deposit(decimal amount)

    {

        if (amount <= 0) Console.WriteLine("Invalid deposit amount.");

        else Console.WriteLine($"Deposit successful! New balance: ${_balance += amount}");

    }

​

    public void Withdraw(decimal amount)

    {

        if (amount <= 0) Console.WriteLine("Invalid withdrawal amount.");

        else if (amount > _balance) Console.WriteLine("Insufficient funds!");

        else Console.WriteLine($"Withdrawal successful! New balance: ${_balance -= amount}");

    }

​

    public void DisplayBalance() => Console.WriteLine($"{_accountHolder}'s balance: ${_balance}");

}

​

class Program

{

    static void Main()

    {

        Console.Write("Enter your name: ");

        BankAccount account = new BankAccount(Console.ReadLine());

​

        while (true)

        {

            Console.WriteLine("\n1. Deposit\n2. Withdraw\n3. Check Balance\n4. Exit");

            Console.Write("Enter choice: ");

            string choice = Console.ReadLine();

​

            if (choice == "4") break;

            Console.Write("Enter amount: ");

            if (!decimal.TryParse(Console.ReadLine(), out decimal amount))

            {

                Console.WriteLine("Invalid input.");

                continue;

            }

​

            if (choice == "1") account.Deposit(amount);

            else if (choice == "2") account.Withdraw(amount);

            else if (choice == "3") account.DisplayBalance();

            else Console.WriteLine("Invalid choice.");

        }

​

        Console.WriteLine("Thank you for using Simple Bank. Goodbye!");

    }

}