#include<iostream>
#include<string>
#include<algorithm>
#include<bits/stdc++.h>
#include<vector>
 
using namespace std;
int MOD=1000000007;

int main(){
    int N,C,ans=0,p; cin >> N >> C;
    for(int i=0; i<C; i++){
        cin >> p;
        ans+=p;
    }
    if(ans%(N+1)!=0) cout << ans/(N+1)+1 << endl;
    else cout << ans/(N+1) << endl;
}
