#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());
    
    int final_position = round(((float)crabs[499]+(float)crabs[500])/2.0f);
    
    int fuel = 0;
    for(int i = 0; i < 1000; i++) fuel += (int)abs((float)final_position-crabs[i]);
    
    cout << fuel << endl;
    
    return 0;
}