/* -*- coding: utf-8 -*-
 *
 * 385.cc: No.385 カップ麺生活 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_M = 10000;
const int MAX_N = 20;

/* typedef */

typedef long long ll;

/* global variables */

int cs[MAX_N], dp[2][MAX_M + 1];
bool primes[MAX_M + 1];

/* subroutines */

void gen_primes(int maxp) {
  memset(primes, true, sizeof(primes));
  primes[0] = primes[1] = false;

  int p;
  for (p = 2; p * p <= maxp; p++)
    if (primes[p])
      for (int q = p * p; q <= maxp; q += p) primes[q] = false;
}

/* main */

int main() {
  int m, n;
  cin >> m >> n;
  for (int i = 0; i < n; i++) cin >> cs[i];

  memset(dp, -1, sizeof(dp));
  dp[0][0] = 0;
  int cur = 0, nxt = 1;

  for (int i = 0; i < n; i++) {
    memcpy(dp[nxt], dp[cur], sizeof(dp[cur]));

    for (int c = cs[i], v = 1; c <= m; c += cs[i], v++)
      for (int j0 = 0, j1 = c; j1 <= m; j0++, j1++)
	if (dp[cur][j0] >= 0) {
	  int d = dp[cur][j0] + v;
	  if (dp[nxt][j1] < d) dp[nxt][j1] = d;
	}

    cur ^= 1, nxt ^= 1;
  }

  gen_primes(m);

  int sum = 0, maxd = 0;
  for (int i = 1; i <= m; i++)
    if (dp[cur][i] >= 0) {
      //printf("dp[%d]=%d(%d)\n", i, dp[cur][i], primes[m - i]);
      if (primes[m - i]) sum += dp[cur][i];
      if (maxd < dp[cur][i]) maxd = dp[cur][i];
    }

  printf("%d\n", sum + maxd);
  return 0;
}