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;
}