#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
using namespace std;
typedef long long ll;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
main(){
    int M,N;
    cin >> M >> N;
    vector<int> V(N);
    rep(i,0,N)cin >> V[i];
    int table[M+1] = {1,1};//0が素数
    for(int i = 2;i <= M;i++){
        if(table[i])continue;
        for(int j = i * 2;j <= M;j += i){
            table[j] = 1;
        }
    }
    int dp[N+1][M+1] = {};
    dp[0][0] = 1;
    rep(i,0,N){
        rep(j,0,M+1)dp[i+1][j] = dp[i][j];
        rep(j,V[i],M+1){
            if(!dp[i+1][j - V[i]])continue;
            dp[i+1][j] = max(dp[i+1][j], dp[i+1][j - V[i]] + 1);
        }
    }
    rep(i,0,M+1)dp[N][i] = max(0, dp[N][i] - 1);

    //arep(i,0,M+1)cout << dp[N][i] << " \n"[i==M];
    ll cnt = 0;
    rep(i,1,M+1){
        if(dp[N][M - i] && !table[i]){
            //cout << i << endl;
            cnt += dp[N][M - i];
            dp[N][M - i] = 0;
        }
    }
    int maxi = 0;
    rep(i,0,M+1)maxi = max(maxi, dp[N][i]);
    cout << cnt + maxi << endl;
}