SEQGAME (DDBB 2019)

#include <bits/stdc++.h>
using namespace std;

const int N = 1005;
const int64_t INF = 1e18;

int n, d;
vector<int> a;

int64_t solve() {
    int64_t ans = INF;
    for(int i = 0; i < n; ++i) {
        int64_t diff = 0;
        for(int j = 0; j < n; ++j)
            diff += abs((j - i) * d + a[i] - a[j]);
        ans = min(ans, diff);
    }

    return ans;
}

int main() {
#ifdef LOCAL
    freopen("in.txt", "r", stdin);
#else
    freopen("SEQGAME.inp", "r", stdin);
    freopen("SEQGAME.out", "w", stdout);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);

    cin >> n >> d;
    for(int i = 1; i <= n; ++i) {
        int x; cin >> x;
        a.push_back(x);
    }

    cout << solve();

    return 0;
}