#!/usr/bin/env python3
from typing import *

def solve(n: int, k: int, a: List[int]) -> bool:
    b = set(a)
    for a_i in reversed(a):
        for i in reversed(range(max(1, a_i - 100), a_i + 1)):
            if ((i + 1) in b and (i + 6) in b) or ((i + 2) in b and (i + 5) in b) or ((i + 3) in b and (i + 4) in b):
                b.add(i)
            if (i + 1) in b and (i + 6) in b and (i + 2) in b and (i + 5) in b and (i + 3) in b and (i + 4) in b:
                return False
    return 1 not in b


YES = 'Yes'
NO = 'No'


# generated by online-judge-template-generator v4.7.1 (https://github.com/online-judge-tools/template-generator)
def main():
    import sys
    tokens = iter(sys.stdin.read().split())
    N = int(next(tokens))
    K = int(next(tokens))
    A = [None for _ in range(K)]
    for i in range(K):
        A[i] = int(next(tokens))
    assert next(tokens, None) is None
    a = solve(N, K, A)
    print(a and YES or NO)


if __name__ == '__main__':
    main()