#include<iostream>
using namespace std;

int main(){
  int n,num;

  while(cin >> n){
    num = 0;
    while(n--){
      num++;
      if(num == 40)num = 1;
    }
    cout << "3C";
    if(num < 10)cout << 0;
    cout << num << endl;
  }
}