contest-10167.cpp

#include<bits/stdc++.h>
#define ll long long
#define pb push_back
#define mp make_Pair
#define ld long double
#define F first
#define S second

using namespace :: std;

const ll maxn=1e5+500;

ll a[maxn];

int main(){
	ll n,m;
	cin>>m>>n;
	for(ll i=0;i<n;i++){
		cin>>a[i];
	}
	ll ans=0;
	sort(a,a+n);
	ll bar=1;
	ll ki=n-2;
	ll cha=a[n-1];
	while(ki>=0){
		if(a[ki]==cha){
			ki--;
			bar++;
		}
		else{
			ll t=cha-a[ki];
			if(t*bar<=m){
				m-=t*bar;
				cha=a[ki];
			}
			else{
				break;
			}
			ki--;
			bar++;
		}
	}
	for(ll i=0;i<=ki;i++){
		ans+=a[i]*a[i];
	}
	ll t=m/bar;
	cha-=t;
	m-=t*bar;
	ans+=(cha-1)*(cha-1)*m;
	ans+=cha*cha*(bar-m);
	cout<<ans;

}