def main():
    from math import sqrt,sin,cos,tan,ceil,radians,floor,gcd,exp,log,log10,log2,factorial,fsum
    from heapq import heapify, heappop, heappush
    from bisect import bisect_left, bisect_right
    from copy import deepcopy
    import copy
    import random
    from collections import deque,Counter,defaultdict
    from itertools import permutations,combinations
    from decimal import Decimal,ROUND_HALF_UP
    #tmp = Decimal(mid).quantize(Decimal('0'), rounding=ROUND_HALF_UP)
    from functools import lru_cache, reduce
    #@lru_cache(maxsize=None)
    from operator import add,sub,mul,xor,and_,or_,itemgetter
    INF = 10**18
    mod1 = 10**9+7
    mod2 = 998244353
    
    #DecimalならPython
    #再帰ならPython!!!!!!!!!!!!!!!!!!!!!!!!!!
    
    
    '''
    大丈夫なところは全部行ける
    全部行けるけど、行かなくていい場所、いってはいけない場所もある
    いや、組み合わせ的に全部行かないとダメっぽい
    いや、行かなくてよいときもあるな
    制約的には各Kにおいて結構大胆な探索ができそう
    '''
    
    N,K = map(int, input().split())
    A = list(map(int, input().split()))
    
    st = set()
    for i in range(K):
        st.add(A[i])
    
    if N in st:
        print('No')
        exit()
    
    if N > 10**5:
        f = True
        for i in range(K):
            if A[i]+3 in st or A[i]+1 in st or A[i]+5 in st:
                f = False
        
        if f:
            print('Yes')
        else:
            print('No')
    
    else:
        dp = [0]*(N+1)
        for i in range(K):
            dp[A[i]] = 1
        for i in reversed(range(1,N+1)):
            if dp[i] == 1:
                if i >= 4 and dp[i-1] == 1:
                    dp[i-4] = 1
                if i >= 5 and dp[i-3] == 1:
                    dp[i-5] = 1
                if i >= 6 and dp[i-5] == 1:
                    dp[i-6] = 1
        
        if dp[1] == 1:
            print('No')
        else:
            print('Yes')
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
if __name__ == '__main__':
    main()