#include <bits/stdc++.h>

using namespace std;

#define endl '\n'
#define i64 long long

int n, k;


void solve(){
	cin >> n >> k;
	vector<int> a(n + 3, 0);
	for (int i = 1; i <= n; i ++) cin >> a[i], a[i] -= i;
	multiset<int> s1, s2;
	i64 sum1 = 0, sum2 = 0;
	i64 ans = 0;
	
	auto blance = [&]() -> void{
		int sz1 = s1.size(), sz2 = s2.size();
		if (sz2 > sz1 + 1){
			i64 now = *s2.begin();
			s1.insert(now);
			sum1 += now;
			sum2 -= now;
			s2.erase(s2.begin());
		}else if (sz1 >= sz2 + 1){
			i64 now = *s1.rbegin();
			s2.insert(now);
			sum1 -= now;
			sum2 += now;
			s1.erase(prev(s1.end()));
		}
	};
	
	auto insert = [&](i64 x) -> void{
		if (s2.empty()){
			s2.insert(x);
			sum2 += x;
		}else{
			i64 y = *s2.begin();
			if (x >= y) {
				s2.insert(x);
				sum2 += x;
			}else{
				s1.insert(x);
				sum1 += x;
			}
		}
		blance();
	};
	
	auto erase = [&](i64 x) -> void{
		if (s1.find(x) != s1.end()){
			s1.erase(s1.find(x));
			sum1 -= x;
		} else s2.erase(s2.find(x)), sum2 -= x;
		blance();
	};
	
	auto query = [&]() -> i64{
		int sz = s1.size() + s2.size();
		if (sz & 1) return *s2.begin();
		else return (*s1.rbegin() + *s2.begin()) / 2;
	};
	
	auto que = [&]() -> bool{
		i64 X = query();
		i64 need = 1ll * s1.size() * X - sum1 + sum2 - 1ll * s2.size() * X;
		if (need > k) return false;
		else return true;
		
	};
	
	
	
	
	for (i64 l = 1, r = 1; r <= n; r ++){
		insert(a[r]);
		while (l <= r && !que()) erase(a[l]), l ++;
		i64 sz = s1.size() + s2.size();
		ans = max(ans, sz);
	}
	
	cout << ans << "\n";
	
	
}

int main(){
	ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	int t = 1;
	cin >> t;
	while (t --) solve();
}