#include <iostream>
using namespace std;
int main(void){
    int a;
 
    while(cin >> a){
        if(a % 39 == 0){
            cout << "3C39" << endl;
        }
        else{
            if(a % 39 < 10){
                cout << "3C0" << a % 39 << endl;
            }
            else{
                cout << "3C" << a % 39 << endl;
            }
        }
    }
}
