#include <bits/stdc++.h>
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define FORR(i,a,b) for (int i=(a);i>=(b);i--)
#define pb push_back
#define pcnt __builtin_popcount
#define show(x) cout<<#x<<" = "<<x<<endl;
#define maxs(x,y) x = max(x,y)
#define mins(x,y) x = min(x,y)
#define fi first
#define se second
#define rng(a) a.begin(),a.end()
#define each(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define sz(x) (int)(x).size()

using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vpii;
typedef set<int> si;
typedef pair<ll,ll> pll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<pll> vpll;
typedef set<ll> sl;
template<typename T>string join(vector<T>&v)
{stringstream s;FOR(i,0,sz(v))s<<' '<<v[i];return s.str().substr(1);}
ll gcd(ll a,ll b){if(a>b)swap(a,b);for(;a>0;b%=a,swap(a,b));return b;}
int modpow(ll a,ll n,int m){if(a==0)return a;ll p=1;for(;n>0;n/=2,a=a*a%m)if(n&1)p=p*a%m;return(int)p;}
void dout(double d){printf("%.12f\n",d);}

const int iinf = 1e9;
const ll linf = 1e18;
const int mod = 1e9+7;
const double pi = acos(-1);
const double eps = 1e-10;

struct Prime{
  vl pl;
  bool is_prime(ll a){
    if(a < 2)return false;
    each(itr, pl){
      if(*itr * *itr > a)return true;
      if(a%*itr == 0)return false;
    }
    return true;
  }
  void init(int a){
    pl.resize(0);
    pl.pb(2);
    pl.pb(3);
    int i = 5;
    while(i <= a){
      if(is_prime(i)) pl.pb(i);
      i += 2;
      if(is_prime(i)) pl.pb(i);
      i += 4;
    }
  }
};

ll n, m, c, dp[10001];
Prime p;
main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> m >> n;
  p.init(1000);
  FOR(i, 1, m + 1) dp[i] = -1;
  FOR(i, 0, n){
    cin >> c;
    FOR(j, c, m + 1) if(dp[j - c] >= 0) maxs(dp[j], dp[j - c] + 1);
  }

  ll ans = 0, ma = 0;
  FORR(i, m, 0){
    if(p.is_prime(m - i)){
      ans += max(0ll, dp[i]);
    }
    maxs(ma, dp[i]);
  }
  cout << ans + ma << endl;
  return 0;
}