import java.util.*;

public class Main {
  public static void main(String[] args){
    String mozi = "yukicoder";
    Scanner cs = new Scanner(System.in);
    String a = cs.next();
    int i = 0;
    while(true){
      if(mozi.charAt(i) != a.charAt(i)){
        System.out.println(mozi.charAt(i));
        break;
      }
      i++;
    }
  }
}