#include <iostream>
using namespace std;

int main() {
  int n, c, p;
  cin >> n >> c;
  int sum = 0;
  int i;
  for (i = 0; i < c; i++) {
    cin >> p;
    sum += p;
  }
  cout << (sum + n) / (n + 1) << endl;
  return 0;
}

