#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 vct[1000005];
int dp[1000005];
signed main(){
	n=read(),k=read();
	for(int i=1;i<=n;i++)a[i]=read(),vct[i]=-1;
	//vector<pair<int,int>> vct;
	for(int i=1;i<=n;i++){
		//如果想要成为答案
		if(a[i]<=i){
			//delete i-1~k prior.
			if(i-a[i]<=min(i-1,k)){
				//1到p删d个 
				vct[i]=i-a[i]+1;
				//vct.push_back({i-a[i],i-1});
			}
		} 
	}
	for(int i=1;i<=n;i++){
		if(vct[i]==-1)continue;
		dp[i]=1;
		for(int j=1;j<i;j++){
			//i-1 个删 vct[i]
			//j-1 个删 vct[j] 
			//j+1~i-1
			if(vct[j]!=-1&&vct[j]<vct[i]&&i-j>=vct[i]-vct[j]){
				dp[i]=max(dp[i],dp[j]+1);
			}
		}//cout<<i<<" "<<vct[i]<<" "<<dp[i]<<"\n"; 
	}
	cout<<*max_element(dp+1,dp+n+1); 
	return 0;
}