#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n,min=0,sum=0,k=0;
	cin >> n;
	int a[n];
	for(int i=0;i<n;i++)
	{
		cin >> a[i];	
	}
	    for(int i=0;i<n-1;i++)
		sum = sum + pow(abs(a[i] - a[i+1]),2);
		
		min = sum;
	
	    int b[n-1];
	
		for(int i=0;i<n-1;i++)
		{
			b[i] = (a[i] + a[i+1])/2;

		}
		int tt = 1;
	vector<vector<int> > d;
	int qwe=0;
	for(int i=0;i<n-1;i++)
	{
	    vector<int> v;
	for(int j=0;j<n;j++)
	{
	    	if((j == tt) && qwe ==0)
	    	{
			v.push_back(b[tt-1]);
			j--;
			qwe = 1;
	    	}
			else
	        v.push_back(a[j]);
	}
	tt++;
	qwe=0;
	d.push_back(v);
	}
	
			sum = 0;
			for(int i=0;i<n-1;i++)
			{
					for(int j=0;j<=n-1;j++)
					{
					    	sum = sum + pow(abs(d[i][j] - d[i][j+1]),2);
					}
					if(sum < min)
					min = sum;
					
					sum = 0;
			}
			
			cout << min;
	
}