#include<cstdio>
#include<iostream>
#include<cstring>
using namespace std;
int main(void)
{
	int i,n,c,p,x,y;
	x=0;
	cin>>n>>c;
	n=n+1;
	for(i=0;i<c;i++){
		cin>>p;
		x=x+p;
	}
	y=x/n;
	if(x%n) y=y+1;
	cout<<y<<endl;
	return 0;
}

