#include<bits/stdc++.h>
using namespace std;
int main(void)
{
	int n,c;
	int p;
	int i,j;
	
	cin>>n>>c;
	
	int sum=0;
	for(i=0;i<c;i++){
		cin>>p;
		sum+=p;
	}
	
	if(sum%(n+1)!=0) cout<<sum/(n+1)+1<<endl;
	else cout<<sum/(n+1)<<endl;
	
	return 0;
}	
	
