s = input()
line = "abcdefghijklmnopqrstuvwxyz"
for i in range(len(s)):
    if i % 2 == 0:
        if s[i] in line:
            continue
        elif s[i] == ' ':
            print('No')
            break
    elif i % 2 != 0:
        if s[i] == ' ':
            continue
        elif s[i] != ' ':
            print('No')
            break
else:
    print('Yes')