#include<bits/stdc++.h>
#define int long long
#define endl '\n'
using namespace std;

const int N = 1e6 + 10;
int a[N];

struct mycmp{
    bool operator() (const int &a, const int &b) const {
        return a > b;
    }
};

multiset<int, mycmp> minn;
multiset<int> maxn;

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

    int ans = 0, shang = 0, xia = 0, l = 1;
    for (int r = 1; r <= n; r ++) {
        maxn.insert(a[r]);
        shang += a[r];
        while (maxn.size() > minn.size() + 1) {
            int p = *maxn.begin(); maxn.erase(maxn.begin());
            shang -= p;
            minn.insert(p);
            xia += p;
        }

        while (minn.size() > maxn.size()) {
            int p = *minn.begin(); minn.erase(minn.begin());
            xia -= p;
            maxn.insert(p);
            shang += p;
        }

        while (minn.size() > 0 && *maxn.begin() < *minn.begin()) {
            int p = *maxn.begin();
            int s = *minn.begin();
            maxn.erase(maxn.begin()), minn.erase(minn.begin());
            shang -= p, xia -= s;
            maxn.insert(s), minn.insert(p);
            shang += s, xia += p;
        }

        while ((shang - *maxn.begin() * maxn.size()) + (*maxn.begin() * minn.size() - xia) > k) {
            if (a[l] >= *maxn.begin()) {
                maxn.erase(a[l]); shang -= a[l];
            } else {
                minn.erase(a[l]); xia -= a[l];
            }

            while (maxn.size() > minn.size() + 1) {
                int p = *maxn.begin(); maxn.erase(maxn.begin());
                shang -= p;
                minn.insert(p);
                xia += p;
            }

            while (minn.size() > maxn.size()) {
                int p = *minn.begin(); minn.erase(minn.begin());
                xia -= p;
                maxn.insert(p);
                shang += p;
            }

            while (minn.size() > 0 && *maxn.begin() < *minn.begin()) {
                int p = *maxn.begin();
                int s = *minn.begin();
                maxn.erase(maxn.begin()), minn.erase(minn.begin());
                shang -= p, xia -= s;
                maxn.insert(s), minn.insert(p);
                shang += s, xia += p;
            }
            l ++;
        }

        ans = max(ans, r - l + 1);
    }

    cout << ans << endl;

    maxn.clear(), minn.clear();
}

signed main () {
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    int t = 1;

    cin >> t;
    while (t --) {
        solve ();
    }
    return 0;
}
/*
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
*/