using System;

using System.Threading.Tasks;

public class Account

{

    private readonly object balanceLock = new object();

    private decimal balance;

    public Account(decimal initialBalance)

    {

        balance = initialBalance;

    }

    public decimal Debit(decimal amount)

    {

        lock (balanceLock)

        {

            if (balance >= amount)

            {

                Console.WriteLine($"Balance before debit :{balance, 5}");

                Console.WriteLine($"Amount to remove     :{amount, 5}");

                balance = balance - amount;

                Console.WriteLine($"Balance after debit  :{balance, 5}");

                return amount;

            }

            else

            {

                return ;

            }

        }

    }

    public void Credit(decimal amount)

    {

        lock (balanceLock)

        {

            Console.WriteLine($"Balance before credit:{balance, 5}");

            Console.WriteLine($"Amount to add        :{amount, 5}");

            balance = balance + amount;

            Console.WriteLine($"Balance after credit :{balance, 5}");

        }

    }

}

class AccountTest

{

    static void Main()

    {

        var account = new Account();

        var tasks = new Task[];

        for (int i = ; i < tasks.Length; i++)

        {

            tasks[i] = Task.Run(() => RandomlyUpdate(account));

        }

        Task.WaitAll(tasks);

    }

    static void RandomlyUpdate(Account account)

    {

        var rnd = new Random();

        for (int i = ; i < ; i++)

        {

            var amount = rnd.Next(, );

            bool doCredit = rnd.NextDouble() < 0.5;

            if (doCredit)

            {

                account.Credit(amount);

            }

            else

            {

                account.Debit(amount);

            }

        }

    }

}