#include <iostream>
using namespace std;
long long a[1001] , n , h , cnt;
int main()
{
cin >> n >> h;
for(int i = n ; i >= 1 ; --i)
cin >> a[i];
for(int i = 1 ; i <= n ; ++i)
{
if(a[i] < a[i - 1])
{
int c = (a[i - 1] - a[i]) / h;
if((a[i - 1] - a[i]) % h != 0)
c++;
a[i] = a[i] + h * c;
cnt = cnt + c;
}
}
cout << cnt;
return 0;
}
// 100 bro