#include <bits/stdc++.h>
using namespace std;
#define int long long   // <-----!!!!!!!!!!!!!!!!!!!

#define rep(i,n) for (int i=0;i<(n);i++)
#define rep2(i,a,b) for (int i=(a);i<(b);i++)
#define rrep(i,n) for (int i=(n)-1;i>=0;i--)
#define rrep2(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define all(a) (a).begin(),(a).end()

typedef long long ll;
typedef pair<int, int> Pii;
typedef tuple<int, int, int> TUPLE;
typedef vector<int> V;
typedef vector<V> VV;
typedef vector<VV> VVV;
typedef vector<vector<int>> Graph;
const int inf = 1e9;
const int mod = 1e9 + 7;

// x > 0
bool isPrime(int n) {
    for (int i = 2; i * i <= n; i++) {
        if (n % i == 0) return false;
    }
    return n != 1;
}

signed main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

    int M, N;
    cin >> M >> N;
    V C(N);
    rep(i, N) cin >> C[i];

    VV dp(N + 1, V(M + 1, -inf)); // Cの部分和 最大何個で作れるか
    dp[0][0] = 0;
    rep(i, N) {
        rep(j, M + 1) {
            if (j < C[i]) {
                dp[i + 1][j] = dp[i][j];
            } else {
                dp[i + 1][j] = max(dp[i][j], dp[i + 1][j - C[i]] + 1);
            }
        }
    }

    // rep(i, N + 1) {
    //     rep(j, M + 1) {
    //         cout << dp[i][j] << " ";
    //     }
    //     cout << endl;
    // }

    int ans = 0;
    rep2(i, 1, M) {
        // cout << M - i << endl;
        if (dp[N][i] > 0 && isPrime(M - i)) {
            // cout << M - i << " " << ans << " " << dp[N][M - i] << endl;
            ans += dp[N][i];
        }
    }

    ans += *max_element(all(dp[N]));
    cout << ans << endl;
}