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