#include <cassert>
#include <iostream>
#include <set>
int main() {
std::cin.tie(NULL)->sync_with_stdio(false);
int n;
long long h;
std::cin >> n >> h;
int m = 0;
long long shift = -h, c = 0;
std::multiset<long long> m_changes[2]; // xpos for each m changes +1
for (int i = 0; i < n; i++) {
long long x;
std::cin >> x;
// shift by h
shift += h;
c -= h * m;
// append to line
m_changes[0].insert(x + shift);
m_changes[1].insert(x - shift);
// normalize
while (true) {
long long x_l = *m_changes[0].rbegin();
long long x_r = *m_changes[1].begin();
if (x_l - shift <= x_r + shift) {
break;
}
m_changes[0].erase(m_changes[0].find(x_l));
m_changes[1].erase(m_changes[1].find(x_r));
x_l -= shift;
x_r += shift;
m_changes[0].insert(x_r + shift);
m_changes[1].insert(x_l - shift);
}
// m*x + c + (x - x0) = (m+1)*x + (c - x0)
m++;
c -= x;
}
while (!m_changes[1].empty()) {
// pop largest
long long x = *m_changes[1].rbegin();
m_changes[1].erase(m_changes[1].find(x));
// apply shift
x += shift;
assert(x >= 0);
// m*x + c = (m-1)*x + (x + c)
m--;
c += x;
}
assert(m == 0);
std::cout << c << std::endl;
return 0;
}
