#pragma GCC optimize("O3", "unroll-loops") // "Ofast"
#pragma GCC target("avx2", "bmi", "bmi2", "lzcnt", "popcnt")
#include <bits/stdc++.h>
//#define int long long
#define vt vector
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
#define ff first
#define ss second
#define dbg(x) cerr << #x << " = " << x << '\n'
#define bit(x, i) ((x) >> (i) & 1)
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using vvt = vt< vt<int> >;
const int N = 1e6 + 5, mod = 1e9 + 7, B = 500;
const ll inf = 1e18 + 7, LIM = (1ll << 60);
const double eps = 1e-6;
int n;
ll h, s[N];
priority_queue<ll> l;
priority_queue<ll, vt<ll>, greater<ll>> r;
void solve () {
cin >> n >> h;
for (int i = 0; i < n; i++) cin >> s[i];
if (h >= *max_element(s, s + n)) {
cout << "0\n";
return;
}
l.push(s[0]), r.push(s[0]);
ll ans = 0;
for (int i = 1; i < n; i++) {
ll lft = l.top() - (i * h), rght = r.top() + (i * h);
if (s[i] < lft) {
l.push(s[i] + (i * h)), l.push(s[i] + (i * h));
l.pop();
r.push(lft - (i * h));
ans += lft - (l.top() - (i * h));
}
else if (s[i] > rght) {
r.push(s[i] - (i * h)), r.push(s[i] - (i * h));
r.pop();
l.push(rght + (i * h));
}
else l.push(s[i] + (i * h)), r.push(s[i] - (i * h));
ans += abs(s[i] - (l.top() - (i * h)));
}
cout << ans;
cout << '\n';
}
bool testcases = 0;
signed main() {
#ifdef ONLINE_JUDGE
freopen(".in", "r", stdin);
freopen(".out", "w", stdout);
#endif
cin.tie(0) -> sync_with_stdio(0);
int test = 1;
if (testcases) cin >> test;
for (int cs = 1; cs <= test; cs++) {
solve();
}
}
