#include <cstdio>
using namespace std;
#define rep2(x,from,to) for(int x=(from);x<(to);++(x))
#define rep(x,to) rep2(x,0,to)
int main() {
	int n;
	while(scanf("%d", &n) != EOF) {
		printf("3C%02d\n", n%39==0?39:n%39);
	}
	return 0;
}