#include <iostream>
#include <algorithm>
#include <string>
using namespace std;
#define int long long
signed main() {
	int n, c, sum = 0; cin >> n >> c;
	for (int i = 0; i < c; i++) {
		int p; cin >> p; sum += p;
	}n++;
	cout << (sum + n - 1) / n << endl;
}
