#include <iostream>

using namespace std;
 
int main() {
  string s;
  cin >> s;
  string ans = "yukicoder";
  int index;
  for(int i = 0; i < 9; i++) {
    if(s[i] != ans[i]) index = i;
  }
  cout << ans[index] << endl;
  return 0;
}