using System;
using System.Linq;
using System.Collections.Generic;


static class NagataKanaIsAGenius {
    public static void Main() {
        int i=0;
        foreach(char c in Console.ReadLine()){
            if(i==0&&(c<'a'||'z'<c)||i==1&&c!=' '){
                Console.WriteLine("No");
                Environment.Exit(0);
            }
            i^=1;
        }
        Console.WriteLine("Yes");
    }
}