#include <iostream>
using namespace std;

int main() {
  int N, C;
  cin >> N >> C;

  int p, sum = 0;
  for (int i = 0; i < C; i++) {
    cin >> p;
    sum += p;
  }

  if (sum % (N + 1) == 0) cout << sum / (N + 1) << endl;
  else cout << sum / (N + 1) + 1 << endl;
  
  return 0;
}
