#include <bits/stdc++.h>
using namespace std;
#define fi first
#define sc second
const int MAXN = 2*1e5+5;
int dp[MAXN], mn[MAXN*4];
pair<int,int> a[MAXN];
void build(int node, int l, int r){
mn[node] = MAXN;
if(l == r)return;
int mid = (l+r)/2, e = node*2,d = node*2+1;
build(e,l,mid); build(d,mid+1,r);
}
void update(int node, int l ,int r, int i, int x){
if(i < l || r < i)return;
if(l == r){
mn[node] = x;
return;
}
int mid = (l+r)/2, e = node*2,d = node*2+1;
update(e,l,mid,i,x); update(d,mid+1,r,i,x);
mn[node] = min(mn[e],mn[d]);
}
int query(int node, int l, int r, int i, int j){
if(j < l || r < i)return MAXN;
if(i <= l && r <= j)return mn[node];
int mid = (l+r)/2, e = node*2,d = node*2+1;
return min(query(e,l,mid,i,j),query(d,mid+1,r,i,j));
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int n,m; cin>>n>>m;
for(int i = 1; i <= n; i++){
int x; cin>>x;
a[i].fi = x - m*i; a[i].sc = -i;
}
a[n+1].fi = -m*(n+1); a[n+1].sc = -(n+1);
sort(a,a+n+2);
build(1,0,n+1);
for(int id = 0; id <= n+1; id++){
int i = -a[id].sc;
if(i != n+1)dp[i] = query(1,0,n+1, i+1,n+1) -i-1;
update(1,0,n+1, i, dp[i]+i);
}
cout<<dp[0]<<"\n";
}
