#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
using P = pair<int, int>;

int main(){
    int m; cin >> m;
    int n; cin >> n;
    vector<int> c(n);
    for(auto &it: c) cin >> it;

    vector<bool> is_prime(10010, true);
    is_prime[0] = is_prime[1] = false;
    for(int i = 2; i*i < is_prime.size(); i++){
        if(!is_prime[i]) continue;
        for(int j = 2; i*j < is_prime.size(); j++) is_prime[i*j] = false;
    }

    vector<int> dp(10010, -(1 << 30));
    dp[0] = 0;
    for(auto &it: c){
        for(int j = 0; j < dp.size(); j++){
            if(j-it < 0 || dp[j-it] < 0) continue;
            dp[j] = max(dp[j], dp[j-it]+1);
        }
    }
    int mx = 0;
    int ans = 0;
    for(int i = 1; i <= m; i++){
        if(dp[i] < 0) continue;
        if(is_prime[m-i]) ans += dp[i];
        mx = max(mx, dp[i]);
    }

    cout << ans+mx << endl;
    return 0;
}