#include <iostream>
#include <algorithm>
#include <math.h>

using namespace std;

int main()
{
    vector<int> crabs(1000);
    
    for(int i = 0; i < 1000; i++) cin >> crabs[i];
    
    sort(crabs.begin(), crabs.end());
    
    vector<int> costs(crabs[999],0);
    
    for(int i = 0; i < costs.size(); i++)
    {
        for(int j = 0; j < 1000; j++)
        {
            int diff = (int)abs((float)i-crabs[j]);
            costs[i] += (diff*(diff+1))/2;
        }
    }
    
    sort(costs.begin(), costs.end());
    
    cout << costs[0] << endl;
    
    return 0;
}