#include<iostream>
#include<cstdio>
#include<cmath>
#include<vector>
#include<queue>
#include<map>
#include<stack>
#include<array>
#include<set>
#include<algorithm>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
void speed()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
}
inline ll read()
{
	ll x = 0, f = 1;
	char ch = getchar();
	while (ch < '0' || ch>'9')
	{
		if (ch == '-')
		{
			f = -1;
		}
		ch = getchar();
	}
	while (ch >= '0' && ch <= '9')
		x = x * 10 + ch - '0', ch = getchar();
	return x * f;
}

void solve()
{
	int n;
	ll k;
	cin >> n >> k;
	vector<int>a(n + 1);
	for (int i = 1; i <= n; i++)
	{
		cin >> a[i];
		a[i] -= i;
	}
	if (n == 1)
	{
		cout << 1 << '\n';
		return;
	}
	multiset<int>s1, s2;
	int l = 1, r = 0;
	ll sum1 = 0, sum2 = 0;
	int ans = 1;
	for (int i = 1; i <= n; i++)
	{
		if (s2.empty())
		{
			s2.insert(a[i]);
			sum2 += a[i];
			continue;
		}
		else if (a[i] < *s2.begin())
		{
			s1.insert(a[i]);
			sum1 += a[i];
		}
		else
		{
			s2.insert(a[i]);
			sum2 += a[i];
		}
		
		while (s1.size() > s2.size())
		{
			sum2 += *s1.rbegin();
			sum1 -= *s1.rbegin();
			s2.insert(*s1.rbegin());
			auto it = s1.end();
			it--;
			s1.erase(it);
		}
		while (1+s1.size() < s2.size())
		{
			sum1 += *s2.begin();
			sum2 -= *s2.begin();
			s1.insert(*s2.begin());
			s2.erase(s2.begin());
		}
		if (!s1.empty() && !s2.empty() && *s1.rbegin() > *s2.begin())
		{
			sum1 -= *s1.rbegin();
			sum2 -= *s2.begin();
			int a1 = *s1.rbegin();
			int a2 = *s2.begin();
			auto it = s1.end();
			it--;
			s1.erase(it);
			s2.erase(s2.begin());
			sum1 += a2;
			sum2 += a1;
			s1.insert(a2);
			s2.insert(a1);
		}
		int len1 = s1.size();
		int len2 = s2.size();
		int temp = len1 + len2;
		while (!s2.empty())
		{
			temp = s1.size() + s2.size();
			if (temp & 1)
			{
				if (sum2 - sum1 - *s2.begin() <= k)
					break;
				else
				{
					auto pos1 = s1.lower_bound(a[l]);
					if (pos1 != s1.end())
					{
						sum1 -= a[l];
						s1.erase(pos1);
					}
					else
					{
						auto pos2 = s2.lower_bound(a[l]);
						sum2 -= a[l];
						s2.erase(pos2);
					}
					l++;
				}
			}
			else
			{
				if (sum2 - sum1 <= k)
					break;
				else
				{
					auto pos1 = s1.lower_bound(a[l]);
					if (pos1 != s1.end())
					{
						sum1 -= a[l];
						s1.erase(pos1);
					}
					else
					{
						auto pos2 = s2.lower_bound(a[l]);
						sum2 -= a[l];
						s2.erase(pos2);
					}
					l++;
				}
			}
		}
		ans = max(ans, i - l + 1);
	}
	cout <</*"ans:"<<*/ ans << '\n';
}
int main()
{
	speed();
	int t;
	cin >> t;
	while (t--)
	{
		solve();
	}
	return 0;
}