#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
#define close ios::sync_with_stdio(false), cin.tie(0), cout.tie(0)

const int N = 1e6 + 5;

int n, k, m;
vector<int> input;
int a[N];

struct SEG
{
#define lson id << 1
#define rson id << 1 | 1
    int sz;
} seg[N << 2];

int getIndex(int v)
{
    return lower_bound(input.begin(), input.end(), v) - input.begin() + 1;
}

void up(int id)
{
    seg[id].sz = seg[lson].sz + seg[rson].sz;
}

void build(int id, int l, int r)
{
    seg[id].sz = 0;
    if (l == r)
        return;
    int mid = (l + r) >> 1;
    build(lson, l, mid);
    build(rson, mid + 1, r);
}

void change(int id, int l, int r, int x, int le)
{
    if (l == r)
    {
        seg[id].sz += le;
        return;
    }
    int mid = (l + r) >> 1;
    if (x <= mid)
        change(lson, l, mid, x, le);
    else
        change(rson, mid + 1, r, x, le);
    up(id);
}

int findKth(int id, int l, int r, int index)
{
    if (l == r)
        return input[l - 1];
    int mid = (l + r) >> 1;
    if (seg[lson].sz >= index)
        return findKth(lson, l, mid, index);
    else
        return findKth(rson, mid + 1, r, index - seg[lson].sz);
}

void solved()
{
    cin >> n >> k;
    input.clear();
    for (int i = 1; i <= n; i++)
    {
        cin >> a[i];
        a[i] -= i;
        input.push_back(a[i]);
    }
    sort(input.begin(), input.end());
    input.erase(unique(input.begin(), input.end()), input.end());
    m = input.size();
    build(1, 1, m);
    int ans = 1, total = 0, sz = 0;
    queue<int> q;
    int preMid = 0;
    for (int i = 1; i <= n; i++)
    {
        if (q.empty())
        {
            ++sz;
            q.push(a[i]);
            int idx = getIndex(a[i]);
            change(1, 1, m, idx, 1);
            preMid = findKth(1, 1, m, (sz + 1) / 2);
            total = 0;
            continue;
        }
        int idx = getIndex(a[i]);
        q.push(a[i]);
        ++sz;
        change(1, 1, m, idx, 1);
        int mid = findKth(1, 1, m, (sz + 1) / 2);
        total += abs(a[i] - preMid);
        if (mid > preMid)
        {
            total += (sz - 1) / 2 * abs(preMid - mid);
            total -= (sz - (sz - 1) / 2) * abs(preMid - mid);
        }
        else if (mid < preMid)
        {
            total += (sz - (sz + 1) / 2) * abs(preMid - mid);
            total -= ((sz + 1) / 2) * abs(preMid - mid);
        }
        preMid = mid;
        while (total > k && !q.empty())
        {
            int v = q.front();
            q.pop();
            --sz;
            total -= abs(v - mid);
            preMid = mid;
            change(1, 1, m, getIndex(v), -1);
            mid = findKth(1, 1, m, (sz + 1) / 2);
            if (mid > preMid)
            {
                total += (sz - 1) / 2 * abs(preMid - mid);
                total -= (sz - (sz - 1) / 2) * abs(preMid - mid);
            }
            else if (mid < preMid)
            {
                total += (sz - (sz + 1) / 2) * abs(preMid - mid);
                total -= ((sz + 1) / 2) * abs(preMid - mid);
            }
            preMid = mid;
        }
        preMid = mid;
        ans = max(ans, (int)q.size());
    }
    cout << ans << endl;
}

signed main()
{
    close;
    int T;
    cin >> T;
    while (T--)
    {
        solved();
    }
    return 0;
}
//因为最后都要变成一样的mid
//考虑