#include <bits/stdc++.h>

using i64 = long long;

void sol() {
    int n;
    std::cin >> n;

    i64 k;
    std::cin >> k;

    std::vector<int> a(n);
    for (int i = 0; i < n; i++) {
        std::cin >> a[i];
        a[i] -= i;
    }

    int ans = 0;
    int lo = 0;

    std::unordered_map<int, int> freq; 
    std::set<int> s;

    for (int hi = 0; hi < n; ++hi) {
        s.insert(a[hi]);
        freq[a[hi]]++;

        auto _mid = std::next(s.begin(), s.size() / 2);
        int mid = *_mid;

        int opt = 0;
        for (auto& p : freq) {
            opt += abs(p.first - mid) * p.second;
        }

        while (opt > k) {
            freq[a[lo]]--;
            if (freq[a[lo]] == 0) {
                freq.erase(a[lo]);
            }
            s.erase(a[lo]);
            lo++;

            opt = 0;
            _mid = std::next(s.begin(), s.size() / 2);
            mid = *_mid;
            for (auto& p : freq) {
                opt += abs(p.first - mid) * p.second;
            }
        }

        ans = std::max(ans, hi - lo + 1);
    }

    std::cout << ans << "\n";
}

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

    int _;
    std::cin >> _;
    while (_--) {
        sol();
    }

    return 0;
}