import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

s = readline().decode().strip()

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

if is_valid: print("Yes")
else: print("No")