s = input()
n = len(s)

flg = False
for i in range(n):
    if i % 2 == 0 and s[i] == " ":
        flg = True
    elif i % 2 != 0 and s[i] != " ":
        flg = True

ans = "Yes"
if flg:
    ans = "No"

print(ans)