#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;
    }

    auto cal= [&](std::priority_queue<int>& lo, std::priority_queue<int, std::vector<int>, std::greater<int>>& hi) {
        if (lo.size() > hi.size() + 1) {
            hi.push(lo.top());
            lo.pop();
        } else if (hi.size() > lo.size()) {
            lo.push(hi.top());
            hi.pop();
        }
        return lo.top();
    };

    int ans = 0;
    int lo = 0;
    std::unordered_map<int, int> freq;
    std::priority_queue<int> q;
    std::priority_queue<int, std::vector<int>, std::greater<int>> gq;
    
    for (int hi = 0; hi < n; ++hi) {
        q.push(a[hi]);
        int mid = cal(q, gq);
        freq[a[hi]]++;
        
        int opt = 0;
        for (auto& _ : freq) {
            opt += abs(_.first - mid) * _.second;
        }

        while (opt > k) {
            freq[a[lo]]--;
            if (freq[a[lo]] == 0) {
                freq.erase(a[lo]);
            }
            lo++;
            q = std::priority_queue<int>();
            gq = std::priority_queue<int, std::vector<int>, std::greater<int>>();
            for (int i = lo; i <= hi; ++i) {
                q.push(a[i]);
                mid = cal(q, gq);
            }
            
            opt = 0;
            for (auto& _ : freq) {
                opt += abs(_.first - mid) * _.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;
}