ol2_15

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;


int main()
{
    ifstream cin("input.txt");

    int n;
    cin>>n;
    vector <long> v1;
    v1.resize(n);
    for(int i = 0; i < n; i++) cin>>v1[i];
    long time = 0;
    int mid = v1.size()/2;
    nth_element(v1.begin(), v1.begin() + mid, v1.end());
    for(int i = 0; i < n; i++){
        time += abs(v1[mid]-v1[i]);
    }
    cout<<time;
    return 0;
}