cf 11a Increasing Sequence

#include <iostream>
#include <cstdio>
using namespace std;
#define LL long long
#define ULL unsigned long long
int main()
{
int n,d;
ULL ans=0;
LL b[2005];
scanf("%d%d",&n,&d);
for(int i=0;i<n;i++)
scanf("%I64d",&b[i]);
for(int i=1;i<n;i++)
if(b[i]<=b[i-1])
{
if(b[i]==b[i-1])
{
ans+=1;
b[i]+=d;
}
else
{
int tmp=(b[i-1]-b[i])/d+1;
ans+=tmp;
b[i]+=tmp*d;
}
}
printf("%I64d\n",ans);
return 0;
}