// Cake Party 2018/12/28

#include <iostream>
using namespace std;

int main() {
    int N, C, cakes = 0;

    cin >> N >> C;
    N++; //私を足す
    for (int i = 0; i < C; i++) {
        int tmp;
        cin >> tmp;
        cakes += tmp;
    }

    if (cakes % N) // ぴったりじゃない
        cout << cakes / N + 1 << '\n';
    else
        cout << cakes / N << '\n';
    return 0;
}
