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//#pragma GCC optimize("Ofast", "unroll-loops")
//#pragma GCC target("sse", "sse2", "sse3", "ssse3", "sse4")

#include <bits/stdc++.h>

#define all(a) a.begin(),a.end()
#define len(a) (int)(a.size())
#define mp make_pair
#define pb push_back
#define fi first
#define se second

using namespace std;

typedef pair<int, int> pii;
typedef long long ll;
typedef long double ld;
template<class T>
using vec = vector<T>;

template<typename T>
bool umin(T &a, T b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}
template<typename T>
bool umax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

#ifdef KoRoVa
#define DEBUG for (bool _FLAG = true; _FLAG; _FLAG = false)
#define LOG(...) print(#__VA_ARGS__" ::", __VA_ARGS__) << endl
template <class ...Ts> auto &print(Ts ...ts) { return ((cerr << ts << " "), ...); }
#else
#define DEBUG while (false)
#define LOG(...)
#endif

const int max_n = -1, inf = 1000111222;




int main() {
//    freopen("input.txt", "r", stdin);
//    freopen("output.txt", "w", stdout);

    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n, mx;
    cin >> n >> mx;
    vector <int> a(n);
    for (auto &i : a) cin >> i;
    multiset <ll> l, r;
    ll k = 0, b = 0;
    ll add_l = 0, add_r = 0;
    auto add = [&] (ll x) {
        if (!r.empty() && *r.begin() + add_r <= x) {
            r.insert(x - add_r);
            return;
        }
        if (!l.empty() && *l.rbegin() + add_l >= x) {
            l.insert(x - add_l);
            return;
        }
        l.insert(x - add_l);
    };
    for (int i = 0; i < n; i++) {
        add_l -= mx;
        add_r += mx;
//        while (!l.empty() && *l.begin() + add_l <= a[i]) {
//            l.erase(l.begin());
//        }
//        while (!l.empty() && *r.begin() + add_r <= a[i]) {
//            r.erase(r.begin());
//        }

        b -= k * mx;

        ++k;

        b -= a[i];
        add(a[i]);
//        r.insert(a[i] - add_r);
        for (int j = 0; j < n; j++) {
//            r.insert(a[i] - add_r);
            add(a[i]);
        }
        while (len(r) > k) {
            l.insert(*r.begin() + add_r - add_l);
            r.erase(r.begin());
        }
        while (len(r) < k) {
            r.insert(*(--l.end()) + add_l - add_r);
            l.erase(--l.end());
        }
    }
    while (k > 0) {
        --k;
        b += *r.rbegin() + add_r;
        r.erase(--r.end());
    }
    cout << b << '\n';
}

/*
KoRoVa!
*/