#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <climits>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include <complex>
using namespace std;

typedef long long ll;

#define REP(i,a,b) for(int i=a; i<b; i++)
#define rep(i,n) REP(i,0,n)

int main(){
  int n;

  while(cin >> n){
    printf("3C%02d\n", (n - 1) % 39 + 1);
  }
}