CurrencyConverter

using System;

namespace CurrencyConverter
{
    class CurrencyConverter
    {
        static void Main()
        {
            double OneUSDToBGN = 1.79549;
            double OneEURToBGN = 1.95583;
            double OneGBPToBGN = 2.53405;
            double OneBGNToEUR = 1 / OneEURToBGN;
            double OneBGNToUSD = 1 / OneUSDToBGN;
            double OneBGNToGBP = 1 / OneGBPToBGN;
            double OneUSDToEUR = OneUSDToBGN / OneEURToBGN;
            double OneUSDToGBP = OneUSDToBGN / OneGBPToBGN;
            double OneEURToUSD = OneEURToBGN / OneUSDToBGN;
            double OneEURToGBP = OneEURToBGN / OneGBPToBGN;
            double OneGBPToUSD = OneGBPToBGN / OneUSDToBGN;
            double OneGBPToEUR = OneGBPToBGN / OneEURToBGN;
            Console.Write("Amount to convert = ");
            double Amount = double.Parse(Console.ReadLine());
            Console.WriteLine("Select Imput Currency: BGN, USD, EUR or GBP");
            string ImputCurrency = Console.ReadLine();
            Console.WriteLine("Select Output Currency: BGN, USD, EUR or GBP");
            string OutputCurrency = Console.ReadLine();
            double BGNConvertToBGN = Amount;
            double BGNConvertToUSD = Amount * OneBGNToUSD;
            double BGNConvertToEUR = Amount * OneBGNToEUR;
            double BGNConvertToGBP = Amount * OneBGNToGBP;
            double USDConvertToUSD = Amount;
            double USDConvertToEUR = Amount * OneUSDToEUR;
            double USDConvertToGBP = Amount * OneUSDToGBP;
            double USDConvertToBGN = Amount * OneUSDToBGN;
            double EURConvertToEUR = Amount;
            double EURConvertToBGN = Amount * OneEURToBGN;
            double EURConvertToUSD = Amount * OneEURToUSD;
            double EURConvertToGBP = Amount * OneEURToGBP;
            double GBPConvertToGBP = Amount;
            double GBPConvertToBGN = Amount * OneGBPToBGN;
            double GBPConvertToUSD = Amount * OneGBPToUSD;
            double GBPConvertToEUR = Amount * OneGBPToEUR;
            while ((ImputCurrency == "BGN") && (OutputCurrency == "USD"))
            {
                Console.WriteLine("converted currency = " + Math.Round(BGNConvertToUSD, 2));
                return;
            }
            while ((ImputCurrency == "BGN") && (OutputCurrency == "EUR"))
            {
                Console.WriteLine("converted currency = " + Math.Round(BGNConvertToEUR, 2));
                return;
            }
            while ((ImputCurrency == "BGN") && (OutputCurrency == "GBP"))
            {
                Console.WriteLine("converted currency = " + Math.Round(BGNConvertToGBP, 2));
                return;
            }
            while ((ImputCurrency == "USD") && (OutputCurrency == "BGN"))
            {
                Console.WriteLine("converted currency = " + Math.Round(USDConvertToBGN, 2));
                return;
            }
            while ((ImputCurrency == "USD") && (OutputCurrency == "EUR"))
            {
                Console.WriteLine("converted currency = " + Math.Round(USDConvertToEUR, 2));
                return;
            }
            while ((ImputCurrency == "USD") && (OutputCurrency == "GBP"))
            {
                Console.WriteLine("converted currency = " + Math.Round(USDConvertToGBP, 2));
                return;
            }
            while ((ImputCurrency == "EUR") && (OutputCurrency == "BGN"))
            {
                Console.WriteLine("converted currency = " + Math.Round(EURConvertToBGN, 2));
                return;
            }
            while ((ImputCurrency == "EUR") && (OutputCurrency == "USD"))
            {
                Console.WriteLine("converted currency = " + Math.Round(EURConvertToUSD, 2));
                return;
            }
            while ((ImputCurrency == "EUR") && (OutputCurrency == "GBP"))
            {
                Console.WriteLine("converted currency = " + Math.Round(EURConvertToGBP, 2));
                return;
            }
            while ((ImputCurrency == "GBP") && (OutputCurrency == "BGN"))
            {
                Console.WriteLine("converted currency = " + Math.Round(GBPConvertToBGN, 2));
                return;
            }
            while ((ImputCurrency == "GBP") && (OutputCurrency == "EUR"))
            {
                Console.WriteLine("converted currency = " + Math.Round(GBPConvertToEUR, 2));
                return;
            }
            while ((ImputCurrency == "GBP") && (OutputCurrency == "USD"))
            {
                Console.WriteLine("converted currency = " + Math.Round(GBPConvertToUSD, 2));
                return;
            }
        }
    }
}