#include "bits/stdc++.h"
using namespace std;

#define ll long long
#define MOD ((int) (1e9) + 7)
#define pii pair<int, int>

#define N 500010

struct Median {
    multiset<int> l, r;
    ll lsum, rsum;

    void init() {
        l.clear(), r.clear();
        lsum = rsum = 0;
    }

    int size() {
        return l.size() + r.size();
    }

    void balance() {
        while (l.size() > (size() + 1) / 2) {
            int el = *l.rbegin();
            lsum -= el, rsum += el;
            l.erase(l.find(el)), r.insert(el);
        }
        while (r.size() > size() / 2) {
            int el  = *r.begin();
            lsum += el, rsum -= el;
            r.erase(r.find(el)), l.insert(el);
        }
    }

    ll cost() {
        if (size() == 0) return 0;
        return 1ll * l.size() * get() - lsum + rsum - 1ll * r.size() * get();
    }

    int get() {
        return *l.rbegin();
    }

    void add(int x) {
        if (size() == 0) {
            l.insert(x); 
            lsum += x;
            return;
        }

        if (x <= get()) {
            l.insert(x);
            lsum += x;
        } else {
            r.insert(x);
            rsum += x;
        }
        balance();
    }

    void remove(int x) {
        assert(size());
        if (x <= get()) {
            assert(l.find(x) != l.end());
            l.erase(l.find(x));
            lsum -= x;
        } else {
            assert(r.find(x) != r.end());
            r.erase(r.find(x));
            rsum -= x;
        }
        balance();
    }
    
} median;

int a[N];

int main() {
#ifdef TEST
    freopen("zz.in", "r+", stdin);
#endif
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int t; cin >> t;
    while (t --) {
        median.init();

        ll n, k; cin >> n >> k;
        for (int i = 1; i <= n; ++ i) cin >> a[i], a[i] -= i;

        int res = 0;
        for (int i = 1, j = 1; i <= n; ++ i) {
            median.add(a[i]);
            while (j < n && median.cost() <= k) median.add(a[++ j]);
            while (median.cost() > k) median.remove(a[j --]);
            res = max(res, j - i + 1);
            median.remove(a[i]);
        }        
        cout << res << '\n';
    }

    return 0;
}