using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;
using System.Security.Cryptography;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var s = ReadLine();
        var flg = true;
        for (var i = 0; i < s.Length; ++i)
        {
            if (i % 2 == 0 && s[i] == ' ') flg = false;
            if (i % 2 == 1 && s[i] != ' ') flg = false;
        }
        WriteLine(flg ? "Yes" : "No");
    }
}