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

int C[21];

int prime[10010];

void p (int m) {
    prime[0] = prime[1] = 1;
    for (int i = 2; i <= m; i++) {
        if (prime[i] != 0) {
        for (int j = 2; i * j <= m; j++) {
            if (!prime[i * j]) prime[i * j] = 1;
        }
        }
    }
}

int check (int pm, int N) {
    for (int i = 0; i < N; i++) {
        if (C[i] <= pm) return i;
    }
    return -1;
}

int main (void) {
    int M, N, pm = 0, t, ans = 0;
    cin.tie(0);
    ios::sync_with_stdio(false);
    cin >> M;
    cin >> N;
    for (int i = 0; i < N; i++) cin >> C[i];
    p(M);
    sort(C, C + N);
    pm = M;
    while ((t = check(pm, N)) != -1) {
        pm -= C[t];
        C[t] = 9999999;
        ans++;
        if (!prime[pm]) pm = M;
    }
    cout << ans << endl;

    return 0;
}