#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>

using namespace std;

int main(){
	
	int n, ans;

	while(true){
		cin >> n;
		if(cin.eof()){
			break;
		}
		ans = (n - 1) % 39 + 1;
		if(ans >= 10){
			printf("3C%d\n", ans);
		}else{
			printf("3C0%d\n", ans);
		}
	}
	
	return 0;
}