#include<bits/stdc++.h>
using namespace std;
#define int long long
int read(){
	int n=0,f=1;
	char ch=getchar();
	while(!isdigit(ch)){
		if(ch=='-')f=-1;
		ch=getchar();
	}
	while(isdigit(ch)){
		n=n*10+ch-'0';
		ch=getchar();
	}
	return n*f;
}
int n,k;
int a[1000005];
int dp[1000005];
int c[1000005];
void modify(int x,int d){
	while(x<=n){
		c[x]=max(c[x],d);
		x+=x&(-x);
	}
}
int query(int x){
	int r=0;
	while(x){
		r=max(r,c[x]),x-=x&(-x);
	}
	return r;
}
bool cmp(pair<int,int> a,pair<int,int> b){
	return a.second-a.first<b.second-b.first;
}
signed main(){
	n=read(),k=read();
	for(int i=1;i<=n;i++)a[i]=read();
	vector<pair<int,int> > vc;
	for(int i=1;i<=n;i++){
		if(a[i]<=i){
			if(i-a[i]<=min(i-1,k)&&n-a[i]>=k){
				vc.push_back({a[i],i});
			}
		} 
	}
	sort(vc.begin(),vc.end(),cmp);
	for(int i=0;i<(int)vc.size();i++){
		pair<int,int> it=vc[i];
		int d=it.first,pos=it.second;
		dp[pos]=query(d-1)+1;
		modify(d,dp[pos]);
	}
	cout<<*max_element(dp+1,dp+n+1); 
	return 0;
}