#include<stdio.h>
 
int main(){
	int a;
	while(scanf("%d", &a) != EOF){
		if(a % 39 == 0) printf("3C%d\n", 39);
		else if(a % 39 < 10) printf("3C0%d\n", a % 39);
		else printf("3C%d\n", a % 39);
	}
	return 0;
}