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