#include "bits/stdc++.h"

using namespace std;

int n, m, a[10], ans = 0;
set<int> used[11];

int get(const vector<int>& a) {
    int res = 0;
    for (auto x : a) {
        res = (res * 1ll * 101 + x) % (int) (1e9 + 7);
    }
    return res;
}

void merge(vector<int>& a, int x) {
    int i = 0;
    while (i < size(a) && a[i] < x) {
        i++;
    }
    a.insert(a.begin() + i, x);
}

void dfs(int j, vector<int> c) {
    if (j == m) {
        int cnt = 0;
        for (auto x : c) {
            cnt += x == 1;
        }
        if (cnt > ans) {
            ans = cnt;
            if (ans == n) {
                cout << n;
                exit(0);
            }
        }
        return;
    }
    {
        int h = get(c);
        if (used[j].find(h) != used[j].end()) {
            return;
        }
        used[j].insert(h);
    }
    vector<pair<vector<int>, int>> dp, dp2;
    dp = {{{}, a[j]}};
    for (auto x : c) {
        dp2.clear();
        for (auto& [arr, y] : dp) {
            for (int v = 0; v <= min(x, y); v++) {
                vector<int> tmp = arr;
                if (v) {
                    merge(tmp, v);
                }
                if (v != x) {
                    merge(tmp, x - v);
                }
                dp2.push_back({tmp, y - v});
            }
        }
        dp = dp2;
        sort(dp.begin(), dp.end());
        dp.resize(unique(dp.begin(), dp.end()) - dp.begin());
    }
    for (auto& [arr, y] : dp) {
        if (!y) {
            dfs(j + 1, arr);
        }
    }
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        cin >> a[i];
        a[i] = min(a[i], n - a[i]);
    }
    dfs(0, {n});
    cout << ans;
}