#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using vi=vector<int>;
using pi=pair<int,int>;
#define F(i,a,b) for(int i=(a);i<=(b);i++)
#define G(i,a,b) for(int i=(a);i>=(b);i--)
#define ms(a,b) memset(a,b,sizeof(a))
#define si(a) ((int)(a).size())
#define all(a) (a).begin(),(a).end()
#define fi first
#define se second
#define pb push_back

const int N=5e5+3;
int n,a[N],b[N],m,rk[N];

struct bit{
	int n;
	ll c[N];
	void init(int m){
		n=m;
		F(i,1,n) c[i]=0;
	}
	void add(int i,ll k){
		for(;i<=n;i+=i&-i) c[i]+=k; 
	}
	ll qry(int i){
		int res=0;
		for(;i>=1;i-=i&-i) res+=c[i];
		return res;
	}
	ll qry(int l,int r){
		if(l>r) return 0;
		return qry(r)-qry(l-1);
	}
}c1,c2;

void add(int x){
	c1.add(rk[x],1);
	c2.add(rk[x],a[x]);
}
void del(int x){
	c1.add(rk[x],-1);
	c2.add(rk[x],-a[x]);
}
int get(){
	int n=c1.qry(m),l=1,r=m,res=0;
	while(l<=r){
		int mid=(l+r)>>1;
		if(c1.qry(mid-1)<=n/2){
			res=mid;
			l=mid+1;
		}else r=mid-1;
	}
	return b[res];
}
ll val(){
	int x=get(),y=upper_bound(b+1,b+m+1,x)-b-1;
	return (ll)c1.qry(y)*x-c2.qry(y)+c2.qry(y+1,m)-(ll)c1.qry(y+1,m)*x;
}

void slv(){
	ll k;
	cin>>n>>k;
	F(i,1,n){
		cin>>a[i];
		a[i]-=i;
		b[++m]=a[i];
	}
	sort(b+1,b+m+1);
	m=unique(b+1,b+m+1)-b-1;
	F(i,1,n) rk[i]=lower_bound(b+1,b+m+1,a[i])-b;
	c1.init(m);
	c2.init(m);
	int j=1,ans=0;
	F(i,1,n){
		add(i);
		while(j<i&&val()>k) del(j++);
		ans=max(ans,i-j+1);
	}
	cout<<ans<<'\n';
}

int main(){
	cin.tie(0)->ios::sync_with_stdio(0);
	int t;
	cin>>t;
	while(t--) slv();
}