n, k = map(int, input().split())
a = list(map(int, input().split()))
d = []
pre = n + 1000
for ai in reversed(a):
    if ai + 100 < pre:
        now = []
        d.append(now)
    now.append(ai-1)
    pre = ai
for di in d:
    mx = di[0]
    mn = di[-1]
    geta = min(mn, 100)
    l = mx - mn + 1 + geta
    dp = [0] * l + [0] * 10
    for ai in di:
        dp[ai - mn + geta] = 1
    for i in range(l - 1, -1, -1):
        if (
            dp[i+1] == dp[i+6] == 1 or
            dp[i+2] == dp[i+5] == 1 or
            dp[i+3] == dp[i+4] == 1
        ):
            dp[i] = 1
    #print(dp)
    if dp[0] == 1:
        print('No')
        exit(0)
print('Yes')