#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) REP(i,0,n)
#define REP(i,s,e) for(int i=(s); i<(int)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for(int i=(int)(s-1); i>=(int)(e); i--)
#define all(r) r.begin(),r.end()
#define rall(r) r.rbegin(),r.rend()

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;

const ll INF = 1e18;
const ll MOD = 1e9 + 7;

template<typename T> T chmax(T& a, const T& b){return a = (a > b ? a : b);}
template<typename T> T chmin(T& a, const T& b){return a = (a < b ? a : b);}

// #define DEBUG_MODE
#ifdef DEBUG_MODE
#define dump(x) cout << #x << " : " << x << " "
#define dumpL(x) cout << #x << " : " << x << '\n'
#define LINE cout << "line : " << __LINE__ << " "
#define LINEL cout << "line : " << __LINE__ << '\n'
#define dumpV(v) cout << #v << " : ["; for(auto& t : v) cout << t << ", "; cout<<"]" << " "
#define dumpVL(v) cout << #v << " : ["; for(auto& t : v) cout << t << ", "; cout<<"]" << endl
#define STOP assert(false)
#else
#define dump(x) 
#define dumpL(x) 
#define LINE 
#define LINEL 
#define dumpV(v) 
#define dumpVL(v) 
#define STOP assert(false)
#endif
#define mp make_pair
 
namespace std {
template<class S, class T>
ostream &operator <<(ostream& out, const pair<S, T>& a) {
    out << '(' << a.fi << ", " << a.se << ')';
    return out;
}
}

struct Sieve {
    vector<int> primes;
    vector<int> _isPrime;
    Sieve(int n) : _isPrime(n+1, 1) {
        buildPrimes();
    }
    void buildPrimes() {
        _isPrime[0] = _isPrime[1] = 0;
        int n = _isPrime.size();
        REP(i, 2, n) {
            if(_isPrime[i]) {
                primes.push_back(i);
                for(int j = i+i; j < n; j += i) _isPrime[j] = false;
            }
        }
    }
    bool isPrime(int i) {
        return _isPrime[i];
    }
};

int main(){
    ll m, n;
    cin >> m >> n;
    vl c(n);
    rep(i, n) cin >> c[i];
    vl dp(m+1, 0LL);
    for(auto&& x: c) if(x < (int)dp.size()) dp[x] = 1;
    rep(i, n) {
        rep(j, dp.size() - c[i]) if(dp[j] > 0) {
            chmax(dp[j+c[i]], dp[j]+1);
        }
    }
    Sieve sieve(m);
    ll ans = *max_element(all(dp));
    rep(i, m) if(sieve.isPrime(m - i)) {
        ans += dp[i];
        dump(i);dumpL(dp[i]);
    }
    cout << ans << '\n';
    dumpL(dp[m]);
    return 0;
}