#include<bits/stdc++.h>

using namespace std;

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