// qdd on Jan 29, 2023

#ifdef qdd
#include <ringo>
#else
#include <bits/stdc++.h>
#define dbg(...)
#define dbgr(x, y)
#endif

using namespace std;

using ll = long long;

template <class T>
istream& operator>>(istream& is, vector<T>& v) {
  for (T& x : v) is >> x;
  return is;
}

template <class T>
ostream& operator<<(ostream& os, const vector<T>& v) {
  bool f = 0;
  for (const T& x : v) (f ? os << ' ' : os) << x, f = 1;
  return os;
}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int a[10][30];

void sol() {
  int n, m, x;
  cin >> n >> m;
  int extra = 0;
  for (int i = 0; i < m; i++) {
    cin >> x;
    if (x == 1 || x == n - 1) {
      i--;
      m--;
      extra++;
    } else {
      for (int j = 0; j < x; j++) a[i][j] = (1 << i);
    }
  }
  int ans = 0, t = 2500000;
  while (t--) {
    for (int i = 0; i < m; i++) {
      shuffle(a[i], a[i] + n, rng);
    }
    map<int, int> mp;
    for (int j = 0; j < n; j++) {
      int sum = 0;
      for (int i = 0; i < m; i++) {
        sum += a[i][j];
      }
      mp[sum]++;
    }
    int now = 0;
    for (auto& [x, y] : mp) {
      if (y == 1) now++;
    }
    ans = max(ans, now);
  }
  cout << min(n, ans + extra) << '\n';
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  sol();
  return 0;
}