#include <bits/stdc++.h>
#define endl '\n'
#define int long long
using namespace std;
using i64 = long long;
const int inf = numeric_limits<int>::max();
struct Info
{
    i64 val = 0;
    int cnt = 0;
};

struct BIT
{
    vector<Info> tree;
    int n;
    BIT(int n) : tree(n + 1), n(n) {}
    inline int lowbit(int n)
    {
        return n & -n;
    }
    void update(int idx, i64 val)
    {
        while (idx <= n)
            tree[idx].val += val, tree[idx].cnt += 1, idx += lowbit(idx);
    }
    void erase(int idx, i64 val)
    {
        while (idx <= n)
            tree[idx].val -= val, tree[idx].cnt -= 1, idx += lowbit(idx);
    }
    pair<i64, i64> querySmall(int idx)
    {
        i64 ans = 0, cnt = 0;
        while (idx)
            ans += (tree[idx].val), cnt += tree[idx].cnt, idx -= lowbit(idx);
        return make_pair(ans, cnt);
    }
    pair<i64, i64> queryBig(int idx)
    {
        auto it = querySmall(idx);
        int id = n;
        i64 res1 = 0, res2 = 0;
        while (id)
            res1 += tree[id].val, res2 += tree[id].cnt, id -= lowbit(id);
        res1 -= it.first, res2 -= it.second;
        return make_pair(res1, res2);
    }
};

// const int N =

void solve()
{
    int n;
    i64 k;
    int timer = 0;
    cin >> n >> k;
    vector<int> a(n + 1);
    vector<int> idx(n + 1);
    vector<int> sorted(n + 1);
    for (int i = 1; i <= n; i++)
    {
        cin >> a[i], a[i] -= i;
        sorted[i] = a[i];
    }
    sort(sorted.begin() + 1, sorted.end());
    sorted.erase(unique(sorted.begin(), sorted.end()), sorted.end());
    // for (int i = 1; i <= n; i++)
    // cout << a[i] << " \n"1[i == n];
    for (int i = 1; i <= n; i++)
        idx[i] = lower_bound(sorted.begin() + 1, sorted.end(), a[i]) - sorted.begin();
    // for (int i = 1; i <= n; i++)
    //     cout << idx[i] << " \n"[i == n];
    BIT tr(sorted.size() + 1);
    multiset<pair<int, int>> s1, s2;
    int L = 1, R = 2;
    auto check = [&]() -> bool
    {
        // cout << L << " " << R << endl;
        auto middle = *s1.rbegin();
        // cout << middle.first << " " << idx[middle.second] << " ";
        auto it1 = tr.queryBig(idx[middle.second]), it2 = tr.querySmall(idx[middle.second]);
        // cout << it1.first << " " << it1.second << ' ' << it2.first << ' ' << it2.second << endl;
        i64 tmp = middle.first * it2.second - it2.first + (it1.first - it1.second * middle.first);
        // cout << tmp << ' ' << (tmp <= k) << endl;
        // cout << "---------------\n";
        return tmp <= k;
    };
    s1.emplace(a[1], 1);
    tr.update(idx[L], a[L]);
    int ans = 1, len = 1;

    while (R <= n)
    {
        // cout << L << " " << R << endl;
        len += 1;
        tr.update(idx[R], a[R]);
        s1.emplace(a[R], R);
        while (s1.size() > (len + 1) / 2)
        {
            auto it = *s1.rbegin();
            s2.insert(it);
            s1.erase(s1.find(it));
        }
        while (s1.size() && s2.size() && s1.rbegin()->first > s2.begin()->first)
        {
            auto it = s2.begin();
            auto it2 = s1.rbegin();
            s1.insert(*it);
            s2.insert(*it2);
            s2.erase(s2.find(*it));
            s1.erase(s1.find(*it2));
        }

        if (!check())
        {
            while (len > 1 && L < R)
            {
                tr.erase(idx[L], a[L]);
                len -= 1;
                if (s1.count(make_pair(a[L], L)))
                    s1.erase(s1.find(make_pair(a[L], L)));
                else if (s2.count(make_pair(a[L], L)))
                    s2.erase(s2.find(make_pair(a[L], L)));
                while (s2.size() && s1.size() < (len + 1) / 2)
                {
                    auto it = *s2.begin();
                    s1.insert(it);
                    s2.erase(s2.find(it));
                }
                while (s1.size() && s2.size() && s1.rbegin()->first > s2.begin()->first)
                {
                    auto it = s2.begin();
                    auto it2 = s1.rbegin();
                    s1.insert(*it);
                    s2.insert(*it2);
                    s2.erase(s2.find(*it));
                    s1.erase(s1.find(*it2));
                }
                L++;
                if (check())
                {
                    // cout << L << "*" << R << endl;
                    ans = max(ans, len);
                    R++;
                    break;
                }
            }
        }
        else
        {
            // cout << L << " " << R << ' ' << len << endl;
            ans = max(ans, len);
            R++;
        }
    }
    cout << ans << endl;
}

signed main()
{
    ios::sync_with_stdio(false), cin.tie(0);
    int T = 1;
    cin >> T;
    while (T--)
        solve();
    // system("pause");
    return 0;
}