#include <iostream>
using namespace std;

int main()
{
	int n;

	while (cin >> n){
		if (n % 39 == 0){
			cout << "3C" << "39" << endl;
		}
		else if (n % 39 < 10){
			cout << "3C0" << n % 39 << endl;
		}
		else {
			cout << "3C" << n % 39 << endl;
		}
	}

	return (0);
}