import sys
import os


# filename = sys.argv[1]
# path = os.path.join(os.getcwd(), filename)
# path = os.path.join(os.getcwd(), 'test1.arg')
# file = open(path, 'r').readlines()


class FSA():
    def __init__(self):
        self.initial_state = '0'
        self.current_letter = None
        self.current_state = self.initial_state
        self.acceptance_state = '0'
        self.alphabet = set()
        self.transition_function = [{'in': '0', 'letter': '0', 'out': '1'},
                                    {'in': '1', 'letter': '1', 'out': '1'},
                                    {'in': '1', 'letter': '0', 'out': '0'},
                                    {'in': '0', 'letter': '1', 'out': '0'}]

    def add_letter_to_alphabet(self, letter):
        self.alphabet.add(letter)

    def add_transition_to_transition_function(self, input_state, output_state, letter):
        obj = {'in': input_state, 'letter': letter, 'out': output_state}
        self.transition_function.append(obj)
        # add letter to alphabet

    def specify_end_state(self, end_state):
        self.end_state = end_state

    def check_text(self, text):
        if text == '':
            return 'YES'

        for letter in text:
            if letter not in self.alphabet:
                return 'NO'

            found_function = None

            for func in self.transition_function:
                if func['in'] == self.current_state and func['letter'] == letter:
                    found_function = func

            if not found_function:
                self.current_state = '0'
            else:
                self.current_state = found_function['out']

            # print('Input text:{} output text:{} current state:{}'.format(text, output_text, self.current_state))
        if self.current_state == self.acceptance_state:
            return 'YES'

        return 'NO'


FSA = FSA()
FSA.alphabet.add('0')
FSA.alphabet.add('1')
# lines = ['10','', '0101']

for line in sys.stdin:
    line = line.rstrip('\n')
    FSA.current_state = FSA.initial_state
    print(FSA.check_text(line))