#include <bits/stdc++.h>

using namespace std;
multiset<int> s1, s2;
const int N = 5e5 + 10;
int a[N], p[N];
int n, k;
void add(int x, int cnt)
{
    s1.insert(x);
    if (int(s1.size()) > (cnt + 1) / 2)
    {
        int k = *s1.rbegin();
        auto f = s1.find(k);
        s1.erase(f);
        s2.insert(k);
    }
}
void del(int x, int cnt)
{
    if (s1.count(x))
    {
        auto k = s1.find(x);
        s1.erase(k);
    }
    else
    {
        auto k = s2.find(x);
        s2.erase(k);
    }
    while (int(s1.size()) > (cnt + 1) / 2)
    {
        int k = *s1.rbegin();
        auto f = s1.find(k);
        s1.erase(f);
        s2.insert(k);
    }
    while (int(s1.size()) < (cnt + 1) / 2)
    {
        int k = *s2.begin();
        auto f = s2.find(k);
        s2.erase(f);
        s1.insert(k);
    }
    while (int(s2.size()) < cnt / 2)
    {
        int k = *s1.rbegin();
        auto f = s1.find(k);
        s1.erase(f);
        s2.insert(k);
    }
}
bool check(int l, int r)
{
    int val = *s1.rbegin();
    int len = r - l + 1;
    int sum = p[r] - p[l - 1];
    // cout << l << " " << r << " " << val << " " << sum << endl;
    if (abs(val * len - sum) <= k)
        return true;
    return false;
}
void solve()
{
    cin >> n >> k;
    for (int i = 1; i <= n; i++)
    {
        cin >> a[i];
        p[i] = p[i - 1] + a[i] - i;
        a[i] -= i;
    }
    int l = 1, r = 1;
    int ans = 1;
    while (r <= n)
    {
        while (r <= n)
        {
            add(a[r], r - l + 1);
            //cout << "add " << l << " " << r << " " << s1.size() << " " << s2.size() << endl;
            if (r <= n && check(l, r))
            {
                ans = max(ans, r - l + 1);
                r++;
            }
            else
                break;
        }
        if (r > n)
            r--;
        while (l <= r && (!check(l, r)))
        {
            del(a[l], r - l);
            //cout << "del " << r - l << " " << l << " " << r << " " << s1.size() << " " << s2.size() << endl;
            l++;
        }
        if (l > r)
            r++;
        if (r == n)
        {
            ans = max(ans, r - l + 1);
            break;
        }
    }
    cout << ans << endl;
}
int main()
{
    cin.tie(0)->sync_with_stdio(false);
    cout.tie(0);
    int t;
    cin >> t;
    while (t--)
    {
        solve();
    }
}
/*
5
7 5
7 2 5 5 4 11 7
6 0
100 3 4 5 99 100
5 6
1 1 1 1 1
5 50
100 200 300 400 500
1 100
3
*/