#include <bits/stdc++.h>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pdd pair<double, double>
#define vi vector<int>
#define vll vector<long long>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<long long, long long>>
#define vpdd vector<pair<double, double>>
#define mp make_pair
#define fi first
#define se second
#define all(v) v.begin(), v.end()
#define pb push_back
#define endl "\n"
#define vvi vector<vector<int>>
#define vvll vector<vector<long long>>

using namespace std;
using LL = long long;
using ULL = unsigned long long;
const int N = 5e5 + 10, INF = 0x3f3f3f3f, mod = 998244353;
const LL bigINF = ((ULL)(1) << 63) - 1;
const double eps = 1e-6;
LL n, k;
vll a(N);

void Sol()
{

    cin >> n >> k;
    for (int i(1); i <= n; ++i)
    {
        cin >> a[i];
        a[i] -= i;
    }

    multiset<int> lo, hi;
    LL minus = 0, plus = 0, l = 1, r = 1, ans = 0;
    while (l <= n && r <= n)
    {
        while (lo.size() > hi.size())
        {
            int mid = *--lo.end();
            minus -= mid;
            plus += mid;
            hi.insert(mid);
            lo.erase(--lo.end());
        }
        while (hi.size() > lo.size() + 1)
        {
            int mid = *hi.begin();
            plus -= mid;
            minus += mid;
            hi.erase(hi.begin());
            lo.insert(mid);
        }
        while (!lo.size() || lo.size() * *--lo.end() - minus + plus - hi.size() * *--lo.end() <= k)
        {
            if (lo.size() <= hi.size())
            {
                plus += a[r];
                hi.insert(a[r]);
                int mid = *hi.begin();
                hi.erase(hi.begin());
                lo.insert(mid);
                plus -= mid;
                minus += mid;
            }
            else
            {
                minus += a[r];
                lo.insert(a[r]);
                int mid = *--lo.end();
                lo.erase(--lo.end());
                hi.insert(mid);
                minus -= mid;
                plus += mid;
            }
            if (lo.size() * *--lo.end() - minus + plus - hi.size() * *--lo.end() <= k)
                ans = max(ans, r - l + 1);
            else
                break;
            r++;
            if (r > n)
                break;
        }
        if (r > n)
            break;
        int old = a[l];
        if (old <= *--lo.end())
        {
            minus -= old;
            lo.erase(lo.lower_bound(old));
        }
        else
        {
            plus -= old;
            hi.erase(hi.lower_bound(old));
        }
        l++;
        r = max(r, l);
    }

    cout << ans << endl;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr), cout.tie(nullptr);

    int t = 1;
    cin >> t;
    while (t--)
    {
        Sol();
    }

    return 0;
}