#include<bits/stdc++.h>
using namespace std;

int n,k,a[500010],l,r,len1,len2;
multiset<int>s1,s2;

void balance(){
	int x;
	while(s1.size()>s2.size()+1){
		x=*s1.rbegin();
		s1.erase(prev(s1.end()));
		s2.insert(x);
		len1-=x;
		len2+=x;
	}
	while(s1.size()<s2.size()){
		x=*s2.begin();
		s1.insert(x);
		s2.erase(s2.begin());
		len1+=x;
		len2-=x;
	}
}

int find(){
	int x=*s1.rbegin();
	int y=*s2.begin();
	if (x*s1.size()-len1+len2-x*s2.size()>k && y*s1.size()-len1+len2-y*s2.size()>k){
		if (*s1.rbegin()>=a[l]) {
			s1.erase(s1.find(a[l]));
			len1-=a[l];
			balance();
		}
		else {
			s2.erase(s2.find(a[l]));
			len2-=a[l];
			balance();
		}
		l++;
		return find();
	}
	return r-l+1;
}

int main(){
	int tt;
	scanf("%d",&tt);
	while(tt--){
		s1.clear();
		s2.clear();
		scanf("%d %d",&n,&k);
		for (int i=1;i<=n;i++){
			scanf("%d",&a[i]);
			a[i]-=i;
		}
//		for (int i=1;i<=n;i++) cout<<a[i]<<' ';
//		cout<<'\n';
		int ans=0;
		l=1;r=0;
		len1=len2=0;
		for (int i=1;i<=n;i++){
			if (s1.empty() || *s1.rbegin()>=a[i]) {
				s1.insert(a[i]);
				len1+=a[i];	
				balance();
			}
			else {
				s2.insert(a[i]);
				len2+=a[i];
				balance();	
			}
			r++;
			ans=max(ans,find());
			//cout<<ans<<' ';
		}
		printf("%d\n",ans);
	}
	return 0;
}