#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef int _loop_int;
#define REP(i,n) for(_loop_int i=0;i<(_loop_int)(n);++i)
#define FOR(i,a,b) for(_loop_int i=(_loop_int)(a);i<(_loop_int)(b);++i)
#define FORR(i,a,b) for(_loop_int i=(_loop_int)(b)-1;i>=(_loop_int)(a);--i)

#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl
#define ALL(a) (a).begin(),(a).end()

#define CHMIN(a,b) a=min((a),(b))
#define CHMAX(a,b) a=max((a),(b))

// mod
const ll MOD = 1000000007ll;
#define FIX(a) ((a)%MOD+MOD)%MOD

// floating
typedef double Real;
const Real EPS = 1e-11;
#define EQ0(x) (abs(x)<EPS)
#define EQ(a,b) (abs(a-b)<EPS)
typedef complex<Real> P;

int m;
int n;
int cup[25];

int main(){
  scanf("%d%d",&m,&n);
  REP(i,n)scanf("%d",cup+i);
  sort(cup,cup+n);
  reverse(cup,cup+n);
  // eratosthenes
  vector<bool> sieve(m+10,true);
  sieve[0] = sieve[1] = false;
  REP(i,m+10){
    if(!sieve[i])continue;
    int it = 2*i;
    while(it<m+10){
      sieve[it] = false;
      it += i;
    }
  }
  // napsack
  vi mxcnt(m+1,-830252521);
  mxcnt[0] = 0;
  REP(i,n){
    int c = cup[i];
    REP(j,m+1){
      if(j+c>m)break;
      CHMAX(mxcnt[j+c],mxcnt[j]+1);
    }
  }
  // answer
  int ans = 0;
  REP(i,m+1){
    if(!sieve[i])continue;
    // i is prime
    // m-x == i causes chance
    // x = m-i
    if(mxcnt[m-i]>0){
      ans += mxcnt[m-i];
    }
  }
  int mx = 0;
  REP(i,m+1)CHMAX(mx,mxcnt[i]);
  ans += mx;
  printf("%d\n",ans);
  return 0;
}