#define _CRT_SECURE_NO_WARNINGS
#include<set>
#include<cmath>
#include<queue>
#include<string>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<unordered_map>
using namespace std;

typedef long long ll;
const int N=500010;
int n,ans;
ll K,sum1,sum2,a[N];
multiset<ll>s1,s2;

inline void insert(ll x)
{
	multiset<ll>::iterator it;
	if(!s1.size())
	{
		s1.insert(x);
		sum1+=x;
		return;
	}
	it=s1.begin();
	if(x>=*it)s1.insert(x),sum1+=x;
	else s2.insert(x),sum2+=x;
	while(s1.size()&&s1.size()>=s2.size()+2)
		it=s1.begin(),sum1-=*it,s2.insert(*it),sum2+=*it,s1.erase(it);
	while(s2.size()&&s1.size()<s2.size())
		it=s2.end(),it--,sum2-=*it,s1.insert(*it),sum1+=*it,s2.erase(it);
}

inline void del(ll x)
{
	multiset<ll>::iterator it;
	it=s1.begin();
	if(x>=*it)it=s1.lower_bound(x),sum1-=*it,s1.erase(it);
	else it=s2.lower_bound(x),sum2-=*it,s2.erase(it);
	while(s1.size()&&s1.size()>=s2.size()+2)
		it=s1.begin(),sum1-=*it,s2.insert(*it),sum2+=*it,s1.erase(it);
	while(s2.size()&&s1.size()<s2.size())
		it=s2.end(),it--,sum2-=*it,s1.insert(*it),sum1+=*it,s2.erase(it);
}

inline bool valid(int i,int j)
{
	int len=j-i+1;
	bool res=0;
	multiset<ll>::iterator it;
	if(len&1)
	{
		it=s1.begin();
		ll pos=*it;
		ll cost=sum1-(s1.size()*pos)+s2.size()*pos-sum2;
		if(cost<=K)
		{
			ans=max(ans,len);
			return 1;
		}
	}
	else
	{
		it=s1.begin();
		ll pos=*it;
		ll cost=sum1-(s1.size()*pos)+s2.size()*pos-sum2;
		if(cost<=K)
		{
			ans=max(ans,len);
			return 1;
		}
		if(!s2.size())return 0;
		it=s2.end();it--;
		pos=*it;
		cost=sum1-(s1.size()*pos)+s2.size()*pos-sum2;
		if(cost<=K)
		{
			ans=max(ans,len);
			return 1;
		}
	}
	return 0;
}

int main()
{
	int T;
	scanf("%d",&T);
	while(T--)
	{
		ans=0;
		scanf("%d%d",&n,&K);
		for(int i=1;i<=n;i++)
			scanf("%lld",&a[i]),a[i]-=i*1ll;
		multiset<ll>::iterator it;
		insert(a[1]);
		for(int i=1,j=1;i<=n;i++)
		{
			while(j<i)insert(a[++j]);
			valid(i,j);
			while(j<n&&valid(i,j))insert(a[++j]);
			valid(i,j);
			del(a[i]);
		}
		printf("%d\n",ans);
	}
	return 0;
}