#include <bits/stdc++.h>
using namespace std;

using pii = pair<int,int>;
using ll = long long;
#define rep(i, j) for(int i=0; i < (int)(j); i++)
#define repeat(i, j, k) for(int i = (j); i < (int)(k); i++)
#define all(v) v.begin(),v.end()
#define debug(x) cerr << #x << " : " << x << endl

template<class T> bool set_min(T &a, const T &b) { return a > b  ? a = b, true : false; }
template<class T> bool set_max(T &a, const T &b) { return a < b  ? a = b, true : false; }
// vector
template<class T> istream& operator >> (istream &is , vector<T> &v) { for(T &a : v) is >> a; return is; }
template<class T> ostream& operator << (ostream &os , const vector<T> &v) { for(const T &t : v) os << "\t" << t; return os << endl; }
// pair
template<class T, class U> ostream& operator << (ostream &os , const pair<T, U> &v) { return os << "<" << v.first << ", " << v.second << ">"; }

const int INF = 1 << 30;
const ll INFL = 1LL << 60;


class Solver {
  public:
    vector<bool> primes(int M) {
        vector<bool> is_prime(M + 1, true);
        is_prime[0] = is_prime[1] = false;
        for(int i = 2; i < is_prime.size(); i++) {
            if(is_prime[i]) {
                for(int j = i * 2; j < is_prime.size(); j += i) is_prime[j] = false;
            }
        }
        return is_prime;
    }
    bool solve() {
        int M, N; cin >> M >> N;
        vector<int> C(N); cin >> C;

        vector<ll> dp(M + 1, -1);
        dp[M] = 0;
        for(int m = M; m >= 0; m--) {
            for(int c : C) {
                if(dp[m] >= 0 and m - c >= 0) set_max(dp[m - c], dp[m] + 1);
            }
        }

        auto is_prime = primes(M);

        ll ans = 0;
        rep(i, M + 1) {
            if(is_prime[i] and dp[i] >= 0) {
                ans += dp[i];
            }
        }
        ll a = *max_element(all(dp));
        if(a >= 0) ans += a;
        cout << ans << endl;
        return 0;
    }
};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    Solver s;
    s.solve();
    return 0;
}