using System;
public class Program
{
    public static void Main()
    {
        //int num = int.Parse(Console.ReadLine() ?? string.Empty);
        //string[] str = (Console.ReadLine() ?? string.Empty).Trim().Split(' ');
        string str = Console.ReadLine() ?? string.Empty;


        string yu = "yukicoder";

        for(int i = 0; i < str.Length; i++)
        {
            if(str[i] != yu[i])
            {
                Console.WriteLine(yu[i]);
                break;
            }
        }
        

    }
}