#include <iostream>
#include <algorithm>
#include <queue>

using namespace std;
using ll = long long;
ll n,k;
const int N = 5e5+100;
int a[N];
int in_que[N];

using Pair = pair<int, int>;

priority_queue<Pair, vector<Pair>, greater<Pair> > xq;
priority_queue<Pair, vector<Pair>, less<Pair> > nq;
ll lssum, mxsum;
int cntls, cntmx;

void toss() {
    while (cntls < cntmx - 1) {
        auto t = xq.top(); xq.pop();
        if (in_que[t.second] == 2) cntmx --, mxsum -= t.first;
        else continue;
        nq.push(t); cntls ++; lssum += t.first;
        in_que[t.second] = 1;
    }
    while (cntls > cntmx) {
        auto t = nq.top(); nq.pop();
        if (in_que[t.second] == 1) cntls --, lssum -= t.first;
        else continue;
        xq.push(t); cntmx ++; mxsum += t.first;
        in_que[t.second] = 2;
    }
}

void add(int x, int idx) {
    if (xq.size() == 0) {
        xq.push(make_pair(x, idx));
        in_que[idx] = 2;
        mxsum += x;
        cntmx ++;
        return;
    } 
    if (x < xq.top().first) {
        nq.push(make_pair(x, idx));
        in_que[idx] = 1;

        lssum += x;
        cntls ++;
    } else {
        xq.push(make_pair(x, idx));
        in_que[idx] = 2;

        mxsum += x;
        cntmx ++;
    }
    toss();
}

void del(int idx) {
    if (in_que[idx] == 1) {
        in_que[idx] = 0;
        cntls --;
        lssum -= a[idx];
    } else if (in_que[idx] == 2) {
        in_que[idx] = 0;
        cntmx --;
        mxsum -= a[idx];
    }
    toss();
}

int get_mid() {
    if (xq.empty()) exit(1);
    return xq.top().first;
}

ll get_tk() {
    return mxsum - 1ll * cntmx * get_mid() + 1ll * cntls * get_mid() - lssum;
}

void sol() {
    cin >> n >> k;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i];
        a[i] -= i;
        in_que[i] = 0;
    }    
    while (!nq.empty()) nq.pop();
    while (!xq.empty()) xq.pop();
    lssum = 0;
    mxsum = 0;
    cntls = 0;
    cntmx = 0;
    int l = 1, ans = 1;
    for (int i = 1; i <= n; ++i) {
        add(a[i], i);
        while (get_tk() > k) {
            del(l);
            ++l;
        }
        ans = max(i - l + 1, ans);
    }
    cout << ans << '\n';
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int T;
    cin >> T;
    while (T --) {
        sol();
    }    
    return 0;
}