#pragma GCC optimize(2)
#include <bits/stdc++.h>
#define int long long
//#define pi 3.1415926
typedef long long ll;
using namespace std;
int mod=998244353;

int fp(int a,int b){
	int ans=1;
	while(b){
		if(b&1) ans*=a,ans%=mod;
		a*=a,a%=mod;
		b>>=1;
	}
	return ans;
}

void solve(){
	int n,k,ans=1;cin>>n>>k;
	vector<int> vec(n+1),pre(n+1);
	for(int i=1;i<=n;i++) cin>>vec[i];
	for(int i=1;i<=n;i++) vec[i]-=i,vec[i]+=1000000;
	for(int len=n;len>=2;len--){
		int p1=1,p2=2;
		int suml=0,sums=0;
		multiset<int,greater<int>> ss;
		multiset<int> ls;
		int mid=vec[1];
		int sizes=0,sizel=0;
		for(;p2<=p1+len-1;p2++){
			if(vec[p2]>=mid) ls.insert(vec[p2]),sizel++,suml+=vec[p2];
			else ss.insert(vec[p2]),sizes++,sums+=vec[p2];
			if(sizel>=sizes+2) sums+=mid,suml-=*ls.begin(),ss.insert(mid),mid=*ls.begin(),ls.erase(ls.begin()),sizel--,sizes++;
			else if(sizes>=sizel+2) suml+=mid,sums-=*ss.begin(),ls.insert(mid),mid=*ss.begin(),ss.erase(ss.begin()),sizel++,sizes--;
		}
		p2--;
		//cout<<*ss.begin()<<" "<<*ls.begin()<<" "<<mid<<'\n';
		//cout<<pre[3]<<"\n";
		while(p2<=n){
			if(suml-sizel*mid+sizes*mid-sums<=k){
				ans=len;
				break;
			}
			bool sp=0;
			if(vec[p1]<mid) ss.erase(vec[p1]),sizes--,sums-=vec[p1];
			else if(vec[p1]>mid) ls.erase((vec[p1])),sizel--,suml-=vec[p1];
			else sp=1;
			p1++;p2++;
			if(vec[p2]<mid) ss.insert(vec[p2]),sizes++,sums+=vec[p2];
			else if(vec[p2]>=mid) ls.insert(vec[p2]),sizel++,suml+=vec[p2];
			if(sp){
				if(sizes>sizel) mid=*ss.begin(),ss.erase(ss.begin()),sizes--,sums-=mid;
				else mid=*ls.begin(),ls.erase(ls.begin()),sizel--,suml-=mid;
			}
			if(sizel>=sizes+2) sums+=mid,suml-=*ls.begin(),ss.insert(mid),mid=*ls.begin(),ls.erase(ls.begin()),sizel--,sizes++;
			else if(sizes>=sizel+2) suml+=mid,sums-=*ss.begin(),ls.insert(mid),mid=*ss.begin(),ss.erase(ss.begin()),sizel++,sizes--;
		}
		if(ans!=1) break;
	}
	cout<<ans<<"\n";
}

signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	int t;cin>>t;while(t--) 
	solve();
	return 0;
}