using System;

class Program
{
    static void Main()
    {
        Console.Write("Enter amount:");
        var amount = double.Parse(Console.ReadLine());
        Console.Write("Enter currency(BGN,USD,EUR,GBP):");
        var currency = Console.ReadLine();
        Console.Write("Enter output currency(BGN,USD,EUR,GBP):");
        var outputCurrency = Console.ReadLine();
        if (currency == "USD" && outputCurrency == "BGN")
        {
            var n = amount * 1.79549;
            Console.WriteLine("BGN:{0}", Math.Round(n, 2));
        }
        else if (currency == "BGN" && outputCurrency == "EUR")
        {
            var n1 = amount / 1.95583;
            Console.WriteLine("EUR:{0}", Math.Round(n1,2));
        }
        else if (currency=="EUR" && outputCurrency=="GBP")
        {
            var n2 = amount * 0.7716599190283401;
            Console.WriteLine("GBP:{0}",Math.Round(n2,2));
        }
        else if (currency=="USD" && outputCurrency=="EUR")
        {
            var n3 = amount * 0.9179913535084802;
            Console.WriteLine("EUR:{0}",Math.Round(n3,2));
        }
        else if (currency == "GBP" && outputCurrency == "USD")
        {
            var n4 = amount * 1.411336032388664;
            Console.WriteLine("USD:{0}", Math.Round(n4, 2));
        }
        else
            Console.WriteLine("Invalid currency");

    }
}