// Source: https://usaco.guide/general/io
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define eb emplace_back // faster than push_back xD
// pbds UwU
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define oset tree<ll, null_type,less<ll>, rb_tree_tag,tree_order_statistics_node_update> // use pair for ms
// my io library :D
#define m1(x) template<class T, class... U> void x(T&& a, U&&... b)
#define m2(x) (ll[]){(x forward<U>(b),0)...}
m1(pr){cout << forward<T>(a); m2(cout << " " <<); cout << "\n";}
m1(re){cin >> forward<T>(a); m2(cin >>);}
ll n, h, base = 1;
vector<ll> treeseg;
ll rangemin(ll a, ll b){
a += base; b += base;
ll s = 1e18;
while (a <= b){
if (a%2 == 1) s = min(s, treeseg[a++]);
if (b%2 == 0) s = min(s, treeseg[b--]);
a /= 2; b /= 2;
}
return s;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
re(n, h);
vector<ll> s(n);
for (ll i{}; i < n; i++) re(s[i]);
if (h == 0) {
vector<ll> t = s;
sort(t.begin(), t.end());
ll x = t[n / 2];
ll cost = 0;
for (ll v : s) cost += abs(v - x);
pr(cost);
return 0;
}
ll maxl = max({*max_element(s.begin(), s.end()), s[0] + (n-1)*h, s[n-1] + (n-1)*h});
while (base <= maxl) base *= 2;
treeseg.resize(2*base);
vector<vector<ll>> dp(n, vector<ll>(maxl+1, 1e18));
for (ll i{}; i <= maxl; i++){
dp[0][i] = abs(s[0]-i);
}
for (ll i = 1; i < n; i++){
fill(treeseg.begin(), treeseg.end(), (ll)1e18);
ll low = max(0LL, s[0] - i*h);
ll high = s[0] + i*h;
for (ll k = low; k <= high; k++){
treeseg[base+k] = dp[i-1][k];
}
for (ll k = base-1; k > 0; k--){
treeseg[k] = min(treeseg[2*k], treeseg[2*k+1]);
}
for (ll j = low; j <= high; j++){
ll l = max(low, j-h), r = min(high, j+h);
dp[i][j] = rangemin(l, r) + abs(j-s[i]);
}
}
ll low = max(0LL, s[0] - (n-1)*h);
ll high = s[0] + (n-1)*h;
ll ans = 1e18;
for (ll i = low; i <= high; i++) ans = min(ans, dp[n-1][i]);
pr(ans);
}
