#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <climits>
#include <cmath>
#include <regex>
#include <queue>

#define rep(i, N) for(int i = 0; i < (N); i++)

using namespace std;

typedef long long ll;

int M, N;
int C[30];
bool is_prime[10010];

void init_prime() {
    rep (i, 10001) {
        is_prime[i] = true;
    }
    is_prime[0] = is_prime[1] = false;
    int i = 2;
    while (i < 10000) {
        for (int j = i*2; j < 10000; j += i) {
            is_prime[j] = false;
        }
        i++;
        while (!is_prime[i]) i++;
    }
}

int dfs(int rem) {
    int ans = 0;
    rep (i, N) {
        if (rem < C[i]) continue;
        int rem2 = rem - C[i];
        if (is_prime[rem2]) {
            is_prime[rem2] = false;
            ans = max(ans, dfs(M) + 1);
            is_prime[rem2] = true;
        } else {
            ans = max(ans, dfs(rem2) + 1);
        }
    }
    return ans;
}

signed main() {
    cin >> M >> N;
    rep (i, N) {
        cin >> C[i];
    }
    init_prime();
    cout << dfs(M) << endl;
}