#include <iostream>
#include <algorithm>
using namespace std;

int dp[10010];
int C[26];
bool is_prime[10010];

int main()
{
    int M, N; cin >> M >> N;

    fill_n(is_prime, M+1, true);
    is_prime[0] = is_prime[1] = false;
    for (int i = 2; i <= M; ++i) {
        if (!is_prime[i]) continue;

        for (int j = i + i; j <= M; j += i) {
            is_prime[j] = false;
        }
    }

    for (int i = 0; i < N; ++i) cin >> C[i];

    fill_n(dp, M+1, -1);
    dp[0] = 0;

    for (int i = 0; i <= M; ++i) {
        for (int j = 0; j < N; ++j) {
            if (i - C[j] >= 0) {
                if (dp[i - C[j]] >= 0) {
                    dp[i] = max(dp[i], dp[i - C[j]] + 1);
                }
            }
        }
    }

    int ans = 0;

    for (int i = 0; i <= M; ++i) if (!is_prime[i] && ans < dp[i]) ans = dp[i];

    for (int i = 0; i <= M; ++i) if (is_prime[i]) {
        ans += max(dp[M - i], 0);
    }

    cout << ans << endl;
}