#include<bits/stdc++.h>
using namespace std;
int main(){
  int N,P,x,sum,get;
  sum = 0;
  cin>>N>>P;

  for(int i = 0 ; i < P ; i++){
    cin>>x;
    sum += x;
  }
  get = sum / (N+1);

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

