Problem:
Score : 200 points

Problem Statement

Evi has N integers a_1,a_2,..,a_N. His objective is to have N equal integers by transforming some of them.

He may transform each integer at most once. Transforming an integer x into another integer y costs him (x-y)^2 dollars. Even if a_i=a_j (i≠j), he has to pay the cost separately for transforming each of them (See Sample 2).

Find the minimum total cost to achieve his objective.

Constraints

1≦N≦100

-100≦a_i≦100

Input

The input is given from Standard Input in the following format:

N
a_1 a_2 ... a_N

Output

Print the minimum total cost to achieve Evi's objective.

Sample Input 1

2
4 8

Sample Output 1

8

Transforming the both into 6s will cost (4-6)^2+(8-6)^2=8 dollars, which is the minimum.

Sample Input 2

3
1 1 3

Sample Output 2

3

Transforming the all into 2s will cost (1-2)^2+(1-2)^2+(3-2)^2=3 dollars. Note that Evi has to pay (1-2)^2 dollar separately for transforming each of the two 1s.

Sample Input 3

3
4 2 5

Sample Output 3

5

Leaving the 4 as it is and transforming the 2 and the 5 into 4s will achieve the total cost of (2-4)^2+(5-4)^2=5 dollars, which is the minimum.

Sample Input 4

4
-100 -100 -100 -100

Sample Output 4

0

Without transforming anything, Evi's objective is already achieved. Thus, the necessary cost is 0.

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
#include <unordered_set>
using namespace std;
int main()
{
	long int n;
	cin>>n;
	long int arr[n];
	int avg=0;
	unordered_set<long int> h;
	for ( int i=0;i<n;i++)
	{
		cin>>arr[i];
		avg+=arr[i];
		h.insert(arr[i]);
	}
	if(h.size()==1)
	{
		cout<<arr[0]<<endl;
		return 0;
	}
	float a=float(avg)/n;
	if(floor(a)==a)
	{
	long int cost=0;
	for( int i=0;i<n;i++)
	{
		cost+=pow(abs(arr[i]-a),2);
	}
	cout<<cost<<endl;
	}
	else
	{
		long int b=(int)a;
		long int c=b+1;
		long int cost_b=0;
		long int cost_c=0;
		for( int i=0;i<n;i++)
			{
				cost_b+=pow(abs(arr[i]-b),2);
				cost_c+=pow(abs(arr[i]-c),2);
			}
		cout<<min(cost_b,cost_c)<<endl;
	}
	return 0;
}