using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        string str = Console.ReadLine();

        var pattern = @"[A-Za-z0-9]@[A-Za-z0-9]+\.[A-Za-z]";

        bool res= Regex.IsMatch(str,pattern);

        if(res==true)

            Console.WriteLine("YES");

        else

            Console.Write("No");

    }

}