## https://yukicoder.me/problems/no/385

def main():
    M = int(input())
    N = int(input())
    C = list(map(int, input().split()))

    dp = [-1] * (M + 1)
    dp[M] = 0
    for m in reversed(range(M + 1)):
        if dp[m] == -1:
            continue

        for c in C:
            if m - c >= 0:
                dp[m - c] = max(dp[m - c], dp[m] + 1)

    # 素数列挙
    primes = []
    primes_flags = [True] * (M + 1)
    primes_flags[0] = False
    primes_flags[1] = False
    for p in range(2, M):
        if not primes_flags[p]:
            continue
        primes.append(p)
        x = 2 * p
        while x <= M:
            primes_flags[x] = False
            x += p

    primes.reverse()
    answer = 0
    for p in primes:
        if dp[p] != -1:
            answer += dp[p]
    
    answer += max(dp)
    print(answer)



if __name__ == "__main__":
    main()