#include <iostream>
#include <queue>
#include <algorithm>
#include <vector>
using ll = long long int;
ll h;
struct LeftNode
{
ll position, time;
LeftNode(ll position, ll time) {this->position = position; this->time = time;}
bool operator>(const LeftNode& other) const
{
ll maxtime = std::max(time, other.time);
ll mypos = position - (maxtime - time) * h;
ll otherpos = other.position - (maxtime - other.time) * h;
return mypos > otherpos;
}
bool operator<(const LeftNode& other) const
{
ll maxtime = std::max(time, other.time);
ll mypos = position - (maxtime - time) * h;
ll otherpos = other.position - (maxtime - other.time) * h;
return mypos < otherpos;
}
ll curtimepos(ll curtime)
{
return position - (curtime - time) * h;
}
};
struct RightNode
{
ll position, time;
RightNode(ll position, ll time) {this->position = position; this->time = time;}
bool operator<(const RightNode& other) const
{
ll maxtime = std::max(time, other.time);
ll mypos = position + (maxtime - time) * h;
ll otherpos = other.position + (maxtime - other.time) * h;
return mypos < otherpos;
}
bool operator>(const RightNode& other) const
{
ll maxtime = std::max(time, other.time);
ll mypos = position + (maxtime - time) * h;
ll otherpos = other.position + (maxtime - other.time) * h;
return mypos > otherpos;
}
ll curtimepos(ll curtime)
{
return position + (curtime-time) * h;
}
};
bool smaller(ll x, LeftNode ln, ll time)
{
ll nodepos = ln.curtimepos(time);
return x < nodepos;
}
bool bigger(ll x, RightNode rn, ll time)
{
ll nodepos = rn.curtimepos(time);
return x > nodepos;
}
int main()
{
std::priority_queue<LeftNode> leftprioq;
std::priority_queue<RightNode,
std::vector<RightNode>,
std::greater<RightNode> > rightprioq;
ll n, x, ans = 0;
std::cin >> n >> h;
std::cin >> x;
leftprioq.push(LeftNode(x, 0));
rightprioq.push(RightNode(x, 0));
for (int i = 1; i < n; ++i)
{
std::cin >> x;
LeftNode leftelem = leftprioq.top();
RightNode rightelem = rightprioq.top();
// std::cout << "i: " << i << "\n";
// std::cout << "borders: " << leftelem.curtimepos(i) << " " << rightelem.curtimepos(i) << "\n";
if (smaller(x, leftelem, i))
{
ll leftnodepos = leftelem.curtimepos(i);
leftprioq.pop();
leftprioq.push(LeftNode(x, i));
leftprioq.push(LeftNode(x, i));
LeftNode nextleftnode = leftprioq.top();
ll nextleftpos = nextleftnode.curtimepos(i);
ans += leftnodepos - x;
// std::cout << "left: " << nextleftpos << " " << leftnodepos << "\n";
rightprioq.push(RightNode(leftnodepos, i));
}
else if (bigger(x, rightelem, i))
{
ll rightnodepos = rightelem.curtimepos(i);
rightprioq.pop();
rightprioq.push(RightNode(x, i));
rightprioq.push(RightNode(x, i));
RightNode nextrightnode = rightprioq.top();
ll nextrightpos = nextrightnode.curtimepos(i);
ans += x - rightnodepos;
// std::cout << "right: " << rightnodepos << " " << nextrightpos << "\n";
leftprioq.push(LeftNode(rightnodepos, i));
}
else
{
leftprioq.push(LeftNode(x, i));
rightprioq.push(RightNode(x, i));
}
}
std::cout << ans;
}
