#include <cstdlib>
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
string bin;
int duljina;
string b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf;
int main(int argc, char *argv[])
{
    b0 = "0000";
    b1 = "0001";
    b2 = "0010";
    b3 = "0011";
    b4 = "0100";
    b5 = "0101";
    b6 = "0110";
    b7 = "0111";
    b8 = "1000";
    b9 = "1001";
    ba = "1010";
    bb = "1011";
    bc = "1100";
    bd = "1101";
    be = "1110";
    bf = "1111";

    cin >> bin;

    for( int i = 0 ; i < bin.size() ; i += 4 ) {

         string Ret;

         for( int j = 0 ; j < 4 ; ++j )
              Ret += bin[ i + j ];
              if (Ret == b0) cout << "0";
              else if (Ret == b1) cout << "1";
              else if (Ret == b2) cout << "2";
              else if (Ret == b3) cout << "3";
              else if (Ret == b4) cout << "4";
              else if (Ret == b5) cout << "5";
              else if (Ret == b6) cout << "6";
              else if (Ret == b7) cout << "7";
              else if (Ret == b8) cout << "8";
              else if (Ret == b9) cout << "9";
              else if (Ret == ba) cout << "a";
              else if (Ret == bb) cout << "b";
              else if (Ret == bc) cout << "c";
              else if (Ret == bd) cout << "d";
              else if (Ret == be) cout << "e";
              else if (Ret == bf) cout << "f";


    }

    system("PAUSE");
    return EXIT_SUCCESS;
}