Word in Plural

using System;

class wordInPlural
{
    static void Main()
    {
        string noun = Console.ReadLine();
        string plural = null;
        if (noun.EndsWith("y"))
        {
            plural = noun.Replace("y", "ies");
            Console.WriteLine(plural);
        }
        else if (noun.EndsWith("o") || noun.EndsWith("ch") || noun.EndsWith("s") || noun.EndsWith("x")|| noun.EndsWith("z"))
        {

            noun = noun + "es";
            Console.WriteLine(noun);
        }
        else
        {
            noun = noun + "s";
            Console.WriteLine(noun);
        }
    }
}