HexToBin

using System;
using System.Text;
class ConvertHexToBin
{
    static void Main()
    {
        string s = Console.ReadLine();
        StringBuilder binRepresent = new StringBuilder();
        for (int i = 0; i < s.Length; i++)
        {
                switch (s[i])
            {
                case 'A': binRepresent.Append("1010"); break;
                case 'B': binRepresent.Append("1011"); break;
                case 'C': binRepresent.Append("1100"); break;
                case 'D': binRepresent.Append("1101"); break;
                case 'E': binRepresent.Append("1110"); break;
                case 'F': binRepresent.Append("1111"); break;
                case '1': binRepresent.Append("0001"); break;
                case '2': binRepresent.Append("0010"); break;
                case '3': binRepresent.Append("0011"); break;
                case '4': binRepresent.Append("0100"); break;
                case '5': binRepresent.Append("0101"); break;
                case '6': binRepresent.Append("0110"); break;
                case '7': binRepresent.Append("0111"); break;
                case '8': binRepresent.Append("1000"); break;
                case '9': binRepresent.Append("1001"); break;
                case '0': binRepresent.Append("0000"); break;
                default:
                    break;
            }
        }
        Console.WriteLine(binRepresent);
    }
}