#include<bits/stdc++.h>

#define int long long
using namespace std;
using ll = long long;
using ld = double;
const ll mod = 1e9 + 7;
const ll inf = 1e9;
const int N = 2e5 + 10;

void solve() {
    int n, k;
    cin >> n >> k;
    vector<int> a(n + 5);
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        a[i] -= i;
    //    cout << a[i] << " ";
    }
    int l = 0, r = -1;
    vector<int> p(n + 5);
    multiset<int, less<int>> q2;
    multiset<int, greater<int>> q1;
    int lx = 1;
    int sum1 = 0, sum2 = 0;
    for (int i = 1; i <= n; i++) {
        if (l <= r && p[l] < i) {
            auto y = q1.find(a[p[l]]);
            if (y != q1.end()) {
                q1.erase(y);
                sum1 -= a[p[l]];
                if (q1.size() < q2.size()) {
                    auto y1 = q2.begin();
                    q1.insert(*y1);
                    sum1 += *y1;
                    sum2 -= *y1;
                    q2.erase(y1);
                }
            } else {
                auto y = q2.find(a[p[l]]);
                sum2 -= *y;
                q2.erase(y);
                if (q1.size() > q2.size() + 1) {
                    auto y1 = q1.begin();
                    q2.insert(*y1);
                    sum1 -= *y1;
                    sum2 += *y1;
                    q1.erase(y1);
                }
            }
            l++;
        }
        int fx = 0;
        while (lx <= n) {
            ans = max(r - l + 1, ans);
            p[++r] = lx++;
            q1.insert(a[p[r]]);
            sum1 += a[p[r]];
            if (q1.size() > q2.size() + 1||(q2.size()&&*q1.begin()>*q2.begin())) {
                auto y1 = q1.begin();
                sum1 -= *y1;
                sum2 += *y1;
                q2.insert(*y1);
                q1.erase(y1);
            }
            if (((*q1.begin() * q1.size() - sum1) + (sum2 - *q1.begin() * q2.size())) > k) {
                auto y = q1.find(a[p[r]]);
                if (y != q1.end()) {
                    q1.erase(y);
                    sum1 -= a[p[r]];
                    if (q1.size() < q2.size()) {
                        auto y1 = q2.begin();
                        q1.insert(*y1);
                        sum1 += *y1;
                        sum2 -= *y1;
                        q2.erase(y1);
                    }
                } else {
                    auto y = q2.find(a[p[r]]);
                    sum2 -= *y;
                    q2.erase(y);
                    if (q1.size() > q2.size() + 1) {
                        auto y1 = q1.begin();
                        q2.insert(*y1);
                        sum1 -= *y1;
                        sum2 += *y1;
                        q1.erase(y1);
                    }
                }
                r--, lx--;
                fx = 1;
            }
            ans = max(ans, r - l + 1);
            if (fx)break;

        }
    }
    cout << ans << '\n';

}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
//    cout<<fixed<<setprecision(2);
//    srand(time(0));
    int T = 1;
    cin >> T;
    while (T--)solve();
    return 0;
}