#include <iostream>
#include <algorithm>
#include <vector>

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;
  }
  int moood=0;
  if(sum%(n+1)!=0) moood =1;
  cout << sum/(n+1) + moood << endl;
  
  
  return 0;
}


