s = str(input())
n = len(s)

for i in range(n):
    c = s[i]
    if i%2 == 1:
        if c != ' ':
            print('No')
            exit()
    else:
        if str.isalpha(c):
            if c != c.lower():
                print('No')
                exit()
        else:
            print('No')
            exit()
else:
    print('Yes')