using System;
using System.Linq;
using System.Security.Cryptography;
using System.Text;

class Program
{
    static void Main(string[] args)
    {
        //Выведите платёжные ссылки для трёх разных систем платежа:
        //pay.system1.ru/order?amount=12000RUB&hash={MD5 хеш ID заказа}
        //order.system2.ru/pay?hash={MD5 хеш ID заказа + сумма заказа}
        //system3.com/pay?amount=12000&curency=RUB&hash={SHA-1 хеш сумма заказа + ID заказа + секретный ключ от системы}

        PayLinkFinder payLinkFinder1 = new PayLinkFinder(new System1(new MD5HashInt()), new Order(13, 12000));
        PayLinkFinder payLinkFinder2 = new PayLinkFinder(new System2(new MD5HashInt()), new Order(4234, 3000));
        PayLinkFinder payLinkFinder3 = new PayLinkFinder(new System3(new SHA1HashInt()), new Order(5321, 12000));

        PayLinkFinder[] payLinkFinders = new PayLinkFinder[] { payLinkFinder1, payLinkFinder2, payLinkFinder3 };

        foreach (var payLinkFinder in payLinkFinders)
        {
            payLinkFinder.Find();
        }
    }
}

public class PayLinkFinder
{
    private IPaymentSystem _paymentSystem;
    private Order _order;

    public PayLinkFinder(IPaymentSystem paymentSystem, Order order)
    {
        _paymentSystem = paymentSystem;
        _order = order;
    }

    public void Find()
    {
        Console.WriteLine(_paymentSystem.GetPayingLink(_order));
        Console.WriteLine();
    }
}

public class MD5HashInt : IHash
{
    public string GetHash(int inputData)
    {
        MD5 md5 = MD5.Create();

        return String.Concat(md5.ComputeHash(BitConverter.GetBytes(inputData)).Select(x => x.ToString("x2")));
    }
}

public class SHA1HashInt : IHash
{
    public string GetHash(int inputData)
    {
        var hash = new SHA1Managed().ComputeHash(Encoding.UTF8.GetBytes(inputData.ToString()));

        return $"{String.Concat(hash.Select(b => b.ToString("x2")))}";
    }
}

public class Order
{
    public readonly int Id;
    public readonly int Amount;

    public Order(int id, int amount)
    {
        Id = id;
        Amount = amount;
    }
}

public abstract class PaymentSystem : IPaymentSystem
{
    protected readonly IHash HashInt;
    protected readonly string PaymentSystemLink;

    protected PaymentSystem(IHash hashInt)
    {
        HashInt = hashInt;
    }

    public abstract string GetPayingLink(Order order);
}

public class System1 : PaymentSystem
{
    public System1(IHash hashInt) : base(hashInt)
    {
    }

    public override string GetPayingLink(Order order)
    {
        return $"pay.system1.ru/order?amount=12000RUB&hash={HashInt.GetHash(order.Id)}";
    }
}

public class System2 : PaymentSystem
{
    public System2(IHash hashInt) : base(hashInt)
    {
    }

    public override string GetPayingLink(Order order)
    {
        return $"order.system2.ru/pay?hash ={HashInt.GetHash(order.Id)}+{HashInt.GetHash(order.Amount)}";
    }
}

public class System3 : PaymentSystem
{
    private int _secretKey = 125623145;

    public System3(IHash hashInt) : base(hashInt)
    {
    }

    public override string GetPayingLink(Order order)
    {
        return $"system3.com/pay?amount=12000&curency=RUB&hash={HashInt.GetHash(order.Id)}+{HashInt.GetHash(order.Amount)}+{HashInt.GetHash(_secretKey)}";
    }
}

public interface IPaymentSystem
{
    public string GetPayingLink(Order order);
}

public interface IHash
{
    public string GetHash(int inputData);
}