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

using namespace std;

int main() {
    int N, K, val, meters = 0;
    vector<int> vec, original_vec;
    cin >> N >> K;

    for(int i = 0; i < N; i++) {
        cin >> val;
        vec.push_back(val);
    }
    sort(vec.begin(), vec.end());
    original_vec = vec;

    if(N == 1)
        meters = 0;
    else if(N == 2)
        meters = abs(vec[1] - (vec[0] + K));
    else {
        size_t first, second;
        if(vec.size() % 2 == 0) {
            first = vec.size() / 2 - 1;
            second = first + 1;
            meters = abs(vec[second] - (vec[first] + K));
            vec[second] = vec[first] + K;
        } else if(vec.size() % 2 == 1) {
            first = vec.size() / 2;
            second = first;
        }
        for(first--, second++; second < vec.size() && first >= 0; first--, second++) {
            meters += abs(vec[first] - (vec[first + 1] - K));
            vec[first] = vec[first + 1] - K;
            meters += abs(vec[second] - (vec[second - 1] + K));
            vec[second] = vec[second - 1] + K;
        }
    }

    cout << meters << endl;
    return 0;
}