from fractions import gcd
from datetime import date, timedelta
from heapq import*
import math
from collections import defaultdict, Counter, deque
import sys
from bisect import *
import itertools
import copy
sys.setrecursionlimit(10 ** 7)
MOD = 10 ** 9 + 7


def main():
    s = list(input())
    for i in range(len(s)):
        if i % 2 == 0:
            if s[i] == " ":
                print("No")
                exit()
        else:
            if s[i] != " ":
                print("No")
                exit()
    print("Yes")
    
    

    

    

if __name__ == '__main__':
    main()