#include<stdio.h>
int main(void)
{
	int c;
	while(scanf("%d",&c)!=EOF){
		if(c>=40){
			c=c%39;
			if(c==0){
				printf("3C39\n");
			}
			else if(c>0 && c<10){
				printf("3C0%d\n",c);
			}
			else{
				printf("3C%d\n",c);
			}
		}
		else if(c>0 && c<10){
			printf("3C0%d\n",c);
		}
		else {
			printf("3C%d\n",c);
		}
	}
	return 0;
}