#include <bits/stdc++.h>

using namespace std;

int main() {
  string dest = "yukicoder";
  string s;
  cin >> s;
  for (int i = 0; i < s.size(); ++i) {
    if (dest[i] != s[i]) {
      cout << dest[i] << '\n';
      break;
    }
  }
  return 0;
}