#include <fstream>

#define ll long long

using namespace std;

ifstream cin("grupuri.in");
ofstream cout("grupuri.out");

const int NMAX = 1e5;

int k, n;
int a[NMAX + 1];

bool check(ll x) {
    ll sum = 0;
    for(int i = 1; i <= n; i++) {
        sum += min((ll) a[i], x);
    }
    return sum >= (ll) k * x;
}

int main()
{
    cin >> k >> n;
    for(int i = 1; i <= n; i++) {
        cin >> a[i];
    }

    ll left = 1, right = 1e12, answer = -1;
    while(left <= right) {
        ll mid = (left + right) / 2;
        if(check(mid)) {
            answer = mid;
            left = mid + 1;
        }
        else {
            right = mid - 1;
        }
    }
    cout << answer << '\n';
    return 0;
}