60pts求调

#include <bits/stdc++.h>
using namespace std;
using ll=long long;

int main()
{
 	ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
	ll n,b=0,ans=0;
	cin>>n;
	ll a[n];
	for(int i=0;i<n;i++)cin>>a[i],b+=a[i];
	b/=n;
	for(int i=0;i<n;i++)
	{
		ans+=pow(a[i]-b,2);
	}
	cout<<ans/n;
	return 0;
}