#include<stdio.h>
int main(void)
{
	int x,ama;
	
	while(1) {
		if(scanf("%d",&x)==EOF){
			break;
		}
		while(n>=39){
			n=n-39;
		}
		if(ama==0) {
			ama=39;
		}
		if(ama<10) {
				printf("3C0%d\n",ama);
		}
		else {
			printf("3C%d\n",ama);
		}
	}	
	return 0;
}