#include <bits/stdc++.h>
using namespace std;
/*
We maintain the artwork from left to right.
For each stack i:
|final_height[i] - final_height[i-1]| ≤ H
We want to change the original heights S[i]
(minimum add/remove cube operations)
to satisfy the safety condition.
*/
priority_queue<long long> leftHeap;
// max-heap: represents upper candidates of adjusted heights
priority_queue<long long, vector<long long>, greater<long long>> rightHeap;
// min-heap: represents lower candidates of adjusted heights
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N;
long long H;
cin >> N >> H;
long long x;
cin >> x; // height of first stack
/*
rs = total number of cube operations (add/remove)
*/
long long rs = 0;
/*
Initially, the first stack must stay at height x.
Both heaps start with x.
*/
leftHeap.push(x);
rightHeap.push(x);
/*
lo and up track how much the allowed range expands
as we move to the right.
Each step allows ±H change.
*/
long long lo = 0, up = 0;
for (int i = 1; i < N; i++) {
lo += H;
up += H;
cin >> x; // original height of current stack
/*
Case 1:
Current stack is TOO LOW to be safe.
We must ADD cubes to raise it.
*/
if (leftHeap.top() > x + lo) {
rs += leftHeap.top() - (x + lo);
leftHeap.push(x + lo);
rightHeap.push(leftHeap.top() - lo - up);
leftHeap.push(x + lo);
leftHeap.pop();
}
/*
Case 2:
Current stack is TOO HIGH to be safe.
We must REMOVE cubes.
*/
else if (rightHeap.top() < x - up) {
rs += (x - up) - rightHeap.top();
rightHeap.push(x - up);
leftHeap.push(rightHeap.top() + lo + up);
rightHeap.push(x - up);
rightHeap.pop();
}
/*
Case 3:
Current stack height is already safe.
No cube operations needed.
*/
else {
leftHeap.push(x + lo);
rightHeap.push(x - up);
}
}
cout << rs << '\n';
return 0;
}
