#include "bits/stdc++.h"

using namespace std;

#ifndef ONLINE_JUDGE
#include "test.h"
#include "dbg.h"
#else
#define debug(...) 42
#define debug_assert(...) 42
#endif


#define IOS ios::sync_with_stdio(0),cin.tie(0)

using ll = long long;
using ull = unsigned long long;

#define endl '\n'
#define int ll

using VI = vector<int>;
using VII = vector<VI>;
using PII = pair<int, int>;
const int inf = 1e18;
const int mod = 1e9 + 7;

template<typename T, typename _Compare = less<>>
struct MySet {
    priority_queue<T, vector<T>, _Compare> p{};
    priority_queue<T, vector<T>, _Compare> ep{};
    int sum;

    MySet() {
        sum = 0;
    }

    void insert(int x) {
        p.emplace(x);
        sum += x;
    }

    void erase(int x) {
        ep.emplace(x);
        sum -= x;
    }

    bool empty() {
        return size() == 0;
    }

    int top() {
        while (!p.empty() && !ep.empty() && p.top() == ep.top()) {
            p.pop();
            ep.pop();
        }
        return p.top();
    }

    void pop() {
        erase(p.top());
    }

    int size() {
        return p.size() - ep.size();
    }
};

struct MidNum {
    MySet<int, greater<>> r{};
    MySet<int> l{};


    void adjust() {
        // debug(r.size(), l.size());
        while (r.size() > l.size()) {
            l.insert(r.top());
            r.pop();
        }
        while (!l.empty() && l.size() - 1 > r.size()) {
            r.insert(l.top());
            l.pop();
        }
    }

    void insert(int x) {
        if (l.empty()||l.top() > x)
            l.insert(x);
        else {
            r.insert(x);
        }
        adjust();
    }

    void erase(int x) {
        if (l.top() >= x) {
            l.erase(x);
        }
        else {
            r.erase(x);
        }

        adjust();
    }

    int opsum() {
        int sums = r.sum - l.sum;
        if (l.size() > r.size()) sums += l.top();
        return sums;
    }
};

void init() {
}


void solve() {
    MidNum mid;
    int n, k;
    cin >> n >> k;
    vector<int> arr(n + 1);
    int l = 1, r = 1;
    for (int i = 1; i <= n; i++) {
        cin >> arr[i];
        arr[i] -= i;
    }
    int maxs = -1;
    for (; r <= n; r++) {
        mid.insert(arr[r]);
        while (k < mid.opsum()) {
            mid.erase(arr[l]);
            l++;
        }
        maxs = max(r - l + 1, maxs);
    }
    cout << maxs << endl;
}

signed main() {
    IOS;
    init();
    // debug(1);
    int t = 1;
    cin >> t;
    while (t--) {
        solve();
    }
}