import sys
import string


def input(): return sys.stdin.readline().strip()


def main():
    def f(s):
        for i, ch in enumerate(S, 1):
            if i % 2 == 0:
                if ch != ' ':
                    return False
            else:
                if ch not in string.ascii_lowercase:
                    return False
        return True

    S = input()
    ans = 'Yes' if f(S) else 'No'
    print(ans)


if __name__ == "__main__":
    main()