#include <bits/stdc++.h>
using namespace std;

#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
const int RANDOM = chrono::high_resolution_clock::now().time_since_epoch().count();
struct chash{
    int operator()(int x) const { return x ^ RANDOM; }
};
typedef gp_hash_table<int, int, chash> hash_t;

typedef long long ll;

#define int long long


const int N = 5e5+5;

int n,k;
int a[N];

struct node{
	int l,r,val;
}tri[4*N],tr2[4*N];

void pushup(int u,node tr[])
{
	tr[u].val = tr[u<<1].val + tr[u<<1|1].val;
}

void build(int u,int l,int r,node tr[])
{
	tr[u] = {l,r,0};
	if(l==r) return;
	int mid = (l+r)>>1;
	build(u<<1,l,mid,tr);
	build(u<<1|1,mid+1,r,tr);
}

int query(int u,int l,int r,node tr[])
{
	if(l<=tr[u].l && tr[u].r<=r) return tr[u].val;
	int res = 0;
	int mid = (tr[u].l + tr[u].r)>>1;
	if(l<=mid) res += query(u<<1,l,r,tr);
	if(r>mid) res += query(u<<1|1,l,r,tr);
	return res;
}

void modify(int u,int p,int x,node tr[])
{
	if(tr[u].l==tr[u].r){
		tr[u].val += x;
		return;
	}
	int res = 0;
	int mid = (tr[u].l + tr[u].r)>>1;
	if(p<=mid) modify(u<<1,p,x,tr);
	if(p>mid) modify(u<<1|1,p,x,tr);
	pushup(u,tr);
}

int ask(auto &ge)
{
	int l = 1,r = n;
	int L = query(1,1,n,tri);
	// cout<<L<<' ';
	while(l<r){
		int mid = (l+r)>>1;
		if(query(1,1,mid,tri)<(L+1)/2) l=mid+1;
		else r=mid;
	}
	int s1 = query(1,1,r,tr2);
	if(query(1,1,r,tri)>(L+1)/2){
		s1 -= (query(1,1,r,tri) - (L+1)/2) * ge[r];	
	} 
	int s2 = query(1,1,n,tr2) - s1;
	int res = (L+1)/2 * ge[r] - s1 + s2 - L/2 * ge[r];
	
	return res; 
}


void solve()
{
	cin>>n>>k;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		a[i] -= i;
	}
	
	int idx = 0;
	set<int>tmp;
	hash_t to,ge;
	// unordered_map<int,int>to,ge;
	for(int i=1;i<=n;i++){
		tmp.insert(a[i]);
	}
	for(int i:tmp){
		to[i] = ++idx;
		ge[idx] = i;
	}
	int ni = n;
	n = idx;
	build(1,1,n,tri),build(1,1,n,tr2);
	int ans = 0;
	for(int i=1,j=1;i<=ni;i++){
		if(i!=1){
			modify(1,to[a[i-1]],-1,tri);
			modify(1,to[a[i-1]],-a[i-1],tr2);
		}
		while(j<=ni){
			modify(1,to[a[j]],1,tri);
			modify(1,to[a[j]],a[j],tr2);
			if(ask(ge)<=k) j++;
			else{
				modify(1,to[a[j]],-1,tri);
				modify(1,to[a[j]],-a[j],tr2);
				break;
			}
		}
		ans = max(ans,j-i);
	}
	cout<<ans<<'\n';
}

signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0),cout.tie(0);

	
	int T;
	cin>>T;
	while(T--){
		solve();
	}
}