#include <bits/stdc++.h>

using namespace std;

ifstream fin("grupuri.in");
ofstream fout("grupuri.out");

const int MAX_N = 100000;

int a[MAX_N + 1], n, k;
int64_t t;

template<typename T1, typename T2>
T2 max(const T1 &x, const T2 &y) {
	return x > y ? x : y;
}

bool f(int64_t t) {
	int64_t s = 0;
	for (int i = 1; i <= n; i++) {
		s += max(a[i], t);
		if (s >= (int64_t)k * t)
			return true;
	}
	return false;
}

int main() {
	fin >> k >> n;
	t = 0;
	for (int i = 1; i <= n; i++) {
		fin >> a[i];
		t += a[i];
	}
	
	int64_t st = 1, dr = t / k, mid;
	while (st <= dr) {
		mid = st + ((dr - st) >> 1);
		if (f(mid) == 0)
			dr = mid - 1;
		else
			st = mid + 1;
	}
	
	fout << dr << "\n";
	
	fin.close();
	fout.close();
	return 0;
}