#include<iostream>
#define endl '\n'
using namespace std;
long long m[1000000];
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    long long br=0,mbr=999999999,d,n,i,pr,a,j;
    cin>>n>>d;
    for(i=0;i<n;i++)
    {
        cin>>m[i];
        if(i!=0)
        {
            if(m[i]==m[i-1]+d){m[i]=-10;}
        }
    }
    for(i=0;i<=n-1;i++)
    {
        if(m[i]!=-10){
        pr=m[i];
       br=0;
        for(j=i+1;j<n;j++)
        {
            if(m[j]!=pr+d&&m[j]!=-10){br++;}pr=pr+d;
        }
        pr=m[i];
        for(j=i-1;j>=0;j--)
        {
            if(m[j]!=pr-d&&m[j]!=-10){br++;}pr=pr-d;
        }
        //cout<<br<<" ";
        mbr=min(mbr,br);}
    }
    cout<<mbr<<endl;
    return 0;
}
/*
8 2
9 4 6 8 8 12 14 1
*/