#include <iostream>
using namespace std;
int main (void){


  int n ,a;


  

  cin >> n ;




  a = n % 39;


    if(  a > 0   &&  a < 10) cout << "3C0"  <<  a  <<endl;
    else if( a >= 10 ) cout << "3C"  <<  a  <<endl;
    else if( a == 0) cout << "3C39"  <<endl;



  return 0 ;

}