//
// Created by liuhao on 2024/4/25.
//
#pragma GCC optimize(1)
#pragma GCC optimize(2)
#pragma GCC optimize(3, "Ofast", "inline")
#include<bits/stdc++.h>
using namespace std;
#define PII pair<int,int>
#define fi first
#define se second
#include<ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define fa tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>
template<class T>
struct Set : fa {
	T operator[](signed x) { return *fa::find_by_order(x); }
	signed rank(T x) { return fa::order_of_key(x); }
};
#undef fa
#define fa tree<pair<T,int>, null_type, less<pair<T,int>>, rb_tree_tag, tree_order_statistics_node_update>
template<class T>
struct multiSet : fa {
	const int inf = 1e8;
	int cnt = 0;
	T operator[](signed x) { return fa::find_by_order(x)->fi; }
	signed rank(T x) { return fa::order_of_key({x, -inf}); }
	void insert(T x) { fa::insert({x, cnt++}); }
	void erase(T x) { fa::erase(fa::lower_bound({x, -inf})); }
	auto lower_bound(T x) { return fa::lower_bound({x, -inf}); }
	auto upper_bound(T x) { return fa::lower_bound({x, inf}); }
};
#undef fa
#define ios ios::sync_with_stdio(0),cin.tie(0),cout.tie(0)
#define int long long
#define endl '\n'
#define vii vector<vector<int>>
struct DSU {
	vector<int> f, siz;
	explicit DSU(int n):f(n+1),siz(n+1,1) {
		iota(f.begin(), f.end(), 0);
	}
	int find(int x) {
		while (x != f[x]) {
			x = f[x] = f[f[x]];
		}
		return x;
	}
	bool same(int x, int y) {
		return find(x) == find(y);
	}
	bool merge(int x, int y) {
		x = find(x);
		y = find(y);
		if (x == y) {
			return false;
		}
		siz[x] += siz[y];
		f[y] = x;
		return true;
	}
	
	int size(int x) {
		return siz[find(x)];
	}
};
struct Fenwick {
	vector<int> fenw;
	int n;
	explicit Fenwick(int _n) : n(_n), fenw(_n) {}
	
	void add(int x, int v) {
		for (int i = x; i < n; i |= i + 1)
			fenw[i] += v;
	}
	
	int operator[](int x) {
		int v{};
		for (int i = x; i >= 0; i = (i & (i + 1)) - 1)
			v += fenw[i];
		return v;
	}
	
	int lower_bound(int v) {
		int k = 31 - __builtin_clz(n), j = -1;
		int tot{};
		for (int i = 1 << k; i; i >>= 1) {
			if (j + i < n && tot + fenw[j + i] < v) {
				tot += fenw[j += i];
			}
		}
		return j + 1;
	}
	
	int upper_bound(int v) {
		int k = 31 - __builtin_clz(n), j = -1;
		int tot{};
		for (int i = 1 << k; i; i >>= 1) {
			if (j + i < n && tot + fenw[j + i] <= v) {
				tot += fenw[j += i];
			}
		}
		return j + 1;
	}
};
char *p1, *p2, buf[100000];
#define getcar() (p1==p2 && (p2=(p1=buf)+fread(buf,1,100000,stdin),p1==p2)?EOF:*p1++)
inline int read() {
	int x = 0, f = 1, c = getcar();
	while (!isdigit(c)) f = (c == '-' ? -f : f), c = getcar();
	while (isdigit(c)) x = x * 10 + c - '0', c = getcar();
	return x * f;
}
inline void write(int n) {
	if (n > 9)write(n / 10);
	putchar('0' + n % 10);
}
signed main() {
#ifdef Liuhao
	freopen("in.txt", "r", stdin);
#else
//	ios;
#endif
	int T=read();
//	cin>>T;
	while(T--){
		int n=read(),k=read();
//		cin>>n>>k;
		vector<int>a(n+1);
		vector<int>b;
		for (int i = 1; i <= n; i++) {
//			cin>>a[i];
			a[i]=read();
			a[i]-=i;
			b.push_back(a[i]);
		}
		std::sort(b.begin(), b.end());
		b.erase(std::unique(b.begin(), b.end()),b.end());
		Fenwick arr1(b.size()+1);
		Fenwick arr2(b.size()+1);
		int l=1;
		int r=0;
		auto check=[&](){
			int mid=arr1.lower_bound((arr1[b.size()]+1)/2);
			int cnt=arr1[mid];
			int sum1=arr2[mid];
			int sum2=arr2[b.size()]-sum1;
			int mid0=b[mid-1];
			int cnt0=arr1[b.size()];
			if(arr1[b.size()]==0)return 0ll;
			return mid0*cnt-sum1+sum2-mid0*(cnt0-cnt);
		};
		int ans=0;
		while(l<n+1){
			while(r<=n&&check()<=k){
				r++;
				int i1 = std::lower_bound(b.begin(), b.end(),a[r])-b.begin()+1;
				arr1.add(i1,1);
				arr2.add(i1,a[r]);
			}
			ans=max(ans,r-l);
			int i1=std::lower_bound(b.begin(), b.end(),a[l])-b.begin()+1;
			arr1.add(i1,-1);
			arr2.add(i1,-a[l]);
			l++;
		}
		write(ans);
		puts("");
//		cout<<ans<<endl;
	}
	return 0;
}