#include<iostream>
using namespace std;
int main() {
	int human, time;
	cin >> human >> time;
	++human;
	int sum = 0;
	int a;
	for (int i = 0; i < time; ++i) {
		cin >> a;
		sum += a;
	}
	cout << sum / human + (sum%human != 0 ? 1 : 0) << endl;
}
