#include <iostream>
#include <cstdio>
using namespace std;
int main(void) {
  int candy, count;

  while(scanf("%d", &candy) != EOF) {
    count = 0;
    while(candy != 0) {
      candy--;
      count++;
      if(count == 39) count = 0;
    }
    if(count == 0) cout << "3C39" << endl;
    else if(count < 10) cout << "3C0" << count << endl;
    else cout << "3C" << count << endl;
  }
  return 0;
}