// Problem: K. Rainbow Subarray
// Contest: Codeforces - The 2023 ICPC Asia Jinan Regional Contest (The 2nd Universal Cup. Stage 17: Jinan)
// URL: https://codeforces.com/gym/104901/problem/K
// Memory Limit: 1024 MB
// Time Limit: 2000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

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

typedef long long i64;

void solve() {
	int n;
	i64 k;
	cin >> n >> k;
	
	vector<i64> a(n + 1);
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
		a[i] -= i;
	}
	
	multiset<i64> s1, s2;
	i64 sum1 = 0, sum2 = 0;
	
	auto balance = [&]() {
		while (s2.size() > s1.size()) {
			i64 x = *s2.begin();
			s1.insert(x);
			s2.erase(s2.begin());
			sum1 += x;
			sum2 -= x;
		} 
		while (s1.size() > s2.size()) {
			i64 x = *s1.rbegin();
			s2.insert(x);
			s1.erase(prev(s1.end()));
			sum2 += x;
			sum1 -= x;
		}
	};
	
	auto add = [&](i64 x) {
		if (s2.empty()) {
			s2.insert(x);
			sum2 += x;
		} else {
			if (x >= *s2.begin()) {
				s2.insert(x);
				sum2 += x;
			} else {
				s1.insert(x);
				sum1 += x;
			}
		}
		balance();
	};
	
	auto pop = [&](i64 x) {
		if (s1.find(x) != s1.end()) {
			s1.erase(x);
			sum1 -= x;
		} else {
			s2.erase(x);
			sum2 -= x;
		}
		balance();
	};
	
	auto check = [&]() -> bool {
		i64 mid = *s2.begin();
		i64 res = sum2 - mid * s2.size() + mid * s1.size() - sum1;
		return res <= k;
	};
	
	int l = 1, ans = 1;
	for (int r = 1; r <= n; r++) {
		add(a[r]);
		while (l <= r && !check()) {
			pop(a[l]);
			l++;
		}
		
		ans = max(ans, r - l + 1);
	}
	
	cout << ans << "\n";
}

signed main() {
	cin.tie(nullptr)->ios::sync_with_stdio(false);
	
	int T;
	cin >> T;
	
	while (T--) {
		solve();
	}

	return 0;	
}