S = input()
invalid = False
i = 0
for h in S:
    i = i + 1
    if i % 2 == 1:
        if type(h) is str:
            pass
        elif type(h) is not str:
            print("No")
            invalid = True
            break
    elif i % 2 == 0:
        if h == " ":
            pass
        else:
            print("No")
            invalid = True
if invalid != True:
    print("Yes")