M = int(input())
N = int(input())
Cs = list(map(int, input().split()))


def primes2(limit):
    ''' returns a list of prime numbers upto limit.
    source: Rossetta code: Sieve of Eratosthenes
    http://rosettacode.org/wiki/Sieve_of_Eratosthenes#Odds-only_version_of_the_array_sieve_above
    '''
    if limit < 2: return []
    if limit < 3: return [2]
    lmtbf = (limit - 3) // 2
    buf = [True] * (lmtbf + 1)
    for i in range((int(limit ** 0.5) - 3) // 2 + 1):
        if buf[i]:
            p = i + i + 3
            s = p * (i + 1) + i
            buf[s::p] = [False] * ((lmtbf - s) // p + 1)
    return [2] + [i + i + 3 for i, v in enumerate(buf) if v]


def solve(M, N, Cs):
    ps = primes2(M)
    dp = [0] * (M + 1)
    for c in Cs:
        if c > M:
            continue
        dp[M - c] = max(dp[M - c], 1)
        for m in range(M, c - 1, -1):
            if dp[m]:
                dp[m - c] = max(dp[m - c], dp[m] + 1)
    return max(dp) + sum(dp[p] for p in ps)

print(solve(M, N, Cs))