#include<iostream>
#include<string>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int main(void){
    int n;
    while(cin>>n){
        n%=39;
        if(n==0)n=39;
        printf("3C%02d\n",n);
    }
	return 0;
}