#include <iostream>
#include <stdio.h>

using namespace std;
 
 int main() {
  int n,a;
  while(cin >> n) {
    a=n % 39;
	cout << "3C";
	if (a==0) a=39;
	if (a<10) cout << '0';
	cout << a << endl;
  }
  return 0;
 }