/*
Things to notice:
1. do not calculate useless values
2. do not use similar names
 
Things to check:
1. submit the correct file
2. time (it is log^2 or log)
3. memory
4. prove your naive thoughts 
5. long long
6. corner case like n=0,1,inf or n=m
7. check if there is a mistake in the ds or other tools you use
8. fileio in some oi-contest

9. module on time 
10. the number of a same divisor in a math problem
11. multi-information and queries for dp and ds problems
*/
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define fi first
#define se second
#define pii pair<long long,long long>
#define mp make_pair
#define pb push_back
const int mod=998244353;
const int inf=0x3f3f3f3f;
const int INF=1e18;
struct Segtree
{
	int ls[20000005],rs[20000005],idx,sz[20000005],sum[20000005];
	void init()
	{
		for(int i=1;i<=idx;i++) ls[i]=rs[i]=sz[i]=sum[i]=0;
		idx=0;
	}
	int build(int l,int r)
	{
		int u=++idx;
		if(l==r) return u;
		int mid=(l+r)>>1;
		ls[u]=build(l,mid),rs[u]=build(mid+1,r);
		return u;
	}
	int update(int id,int l,int r,int x,int y)
	{
		int u=++idx;
		ls[u]=ls[id],rs[u]=rs[id],sz[u]=sz[id],sum[u]=sum[id];
		if(l==r)
		{
			sz[u]++,sum[u]+=y;
			return u; 
		}
		int mid=(l+r)>>1;
		if(x<=mid) ls[u]=update(ls[id],l,mid,x,y);
		else rs[u]=update(rs[id],mid+1,r,x,y);
		sz[u]=sz[ls[u]]+sz[rs[u]];
		sum[u]=sum[ls[u]]+sum[rs[u]];
		return u; 
	}
	int query(int p,int q,int l,int r,int k)
	{
//		cout<<"query: "<<p<<" "<<q<<" "<<l<<" "<<r<<" "<<k<<"\n";
		if(sz[p]-sz[q]<k) return -INF;
		if(l==r) 
		{
			int x=sum[p]/sz[p];
			return k*x;
		}
		int mid=(l+r)>>1;
		if(sz[rs[p]]-sz[rs[q]]>=k) return query(rs[p],rs[q],mid+1,r,k);
		else return sum[rs[p]]-sum[rs[q]]+query(ls[p],ls[q],l,mid,k-(sz[rs[p]]-sz[rs[q]]));
	}
	int kth(int p,int q,int l,int r,int k)
	{
		if(sz[p]-sz[q]<k) return INF;
		if(l==r) return l; 
		int mid=(l+r)>>1;
		if(sz[rs[p]]-sz[rs[q]]>=k) return kth(rs[p],rs[q],mid+1,r,k);
		else return kth(ls[p],ls[q],l,mid,k-(sz[rs[p]]-sz[rs[q]]));
	}
}st;
int n,K,a[500005],b[500005],m,Rt[500005];
bool chk(int l,int r)
{
	if(l==r) return 1;
	int lim=st.kth(Rt[r],Rt[l-1],1,m,(r-l+2)/2);
	int sel=b[lim];
	int cl=(r-l+2)/2,cr=r-l+1-cl;
	int cst=sel*cl-(st.query(Rt[r],Rt[l-1],1,m,r-l+1)-st.query(Rt[r],Rt[l-1],1,m,cr));
	if(cr) cst+=st.query(Rt[r],Rt[l-1],1,m,cr)-cr*sel;
//	cout<<l<<" "<<r<<" "<<cst<<"\n";
	return cst<=K;
}
void solve()
{
	st.init();
	cin>>n>>K;
	for(int i=1;i<=n;i++) cin>>a[i],a[i]-=i,b[++m]=a[i];
	sort(b+1,b+1+m),m=unique(b+1,b+1+m)-b-1;
	Rt[0]=st.build(1,m);
	for(int i=1;i<=n;i++) Rt[i]=st.update(Rt[i-1],1,m,lower_bound(b+1,b+1+m,a[i])-b,a[i]);
	int maxx=1;
	for(int l=1,r=1;l<=n;l++)
	{
		r=max(r,l);
		while(r+1<=n&&chk(l,r+1)) r++;
		maxx=max(maxx,r-l+1);
	}
	cout<<maxx<<"\n"; 
}
signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int _=1;
	cin>>_;
	while(_--) solve();
	return 0;
}