#include<bits/stdc++.h>
using namespace std; 
typedef long long ll;
const int M = 5e5 + 10;
long long t,n,k;
long long a[M];
multiset<long long> s1,s2;
long long sum1=0,sum2=0;
void adjust(){
	while(s1.size()>s2.size()+1){
		multiset<long long>::iterator it=(--s1.end());
		sum2+=*it; sum1-=*it;
		s2.insert(*it);
		s1.erase(it);
	}
	while(s1.size()<s2.size()){
		multiset<long long>::iterator it=s2.begin();
		sum1+=*it; sum2-=*it;
		s1.insert(*it); s2.erase(it);
	}
}
void add(long long tmp){
	//cout<<*s1.rbegin();
	if(s1.size()==0||tmp<=*(s1.rbegin())){
		s1.insert(tmp);
		sum1+=tmp;
	}
	else {
		s2.insert(tmp); sum2+=tmp;
	}
	adjust();
}
void del(long long tmp){
	multiset<long long>::iterator it=s1.lower_bound(tmp);
	if(it!=s1.end()){
		s1.erase(it);
		sum1-=tmp;
	}
	else{
		it=s2.lower_bound(tmp); s2.erase(it);
		sum2-=tmp;
	}
	adjust();
}
void solve(){
	cin>>n>>k;
	s1.clear(); s2.clear(); sum1=sum2=0;
	for(int i=1;i<=n;i++){
		cin>>a[i]; a[i]-=i;
	}
	if(n==1) {
		cout<<1<<endl; return;
	}
	long long mid=a[1],sum=0,res=1;
	add(a[1]);
	for(long long i=1,j=2;i<=j&&j<=n&&i<=n;i++){
		while(j<=n){
			add(a[j]); long long tmp=*(s1.rbegin());
			sum=tmp*1ll*s1.size()-sum1+sum2-tmp*s2.size();
			//cout<<tmp<<" "<<sum<<" "<<*s1.begin()<<" "<<*s2.begin()<<' ';
			//cout<<tmp<<" ";
			if(sum<=k&&j<=n) {
				res=max(res,j-i+1); j++;
			}
			else {
				del[a[j]];	break;
			}
			
			
		}
		del(a[i]);
	}
	cout<<res<<endl;
}
int main(){
	cin>>t;
	while(t--){
		solve();
	}
}