#include<iostream>
using namespace std;
int main (){
  int N,C,c;
  int sum=0;
  cin >> N >> C ;
  for (int i=0; i<C; i++){
    cin >> c ;
    sum=sum+c;
  }
  if(sum%(N+1)==0){
    cout << sum/(N+1) << endl;
  }else {
    cout << sum/(N+1)+1 << endl;
  }
}

