#include<stdio.h>
int main(void)
{
	int a;
	while(scanf("%d",&a)!=EOF){
		if(a%39==0) printf("3c39\n");
		else{
			if(a%39>=10) printf("3C%d\n",a%39);
			else printf("3C0%d\n",a%39);
		}
	}
	return 0;
}