#include<bits/stdc++.h>
using namespace std;

int main(){
  int n;
  while(cin>>n){
    if(n%39==0){
      cout<<"3C39"<<endl;
    }
    else if(n%39<10){
      cout<<"3C0"<<n%39<<endl;
    }
    else{
      cout<<"3C"<<n%39<<endl;
    }
  }
  return 0;
}
  