#include <bits/stdc++.h>
using namespace std;
#define int ll

#define fi first
#define se second
#define Mp make_pair
#define pb push_back
#define SZ(x) (int((x).size()))

typedef double db;
typedef long long ll;
typedef vector<ll> vi;
typedef pair<int, int> pii;

#define lc(k) (k << 1)
#define rc(k) (lc(k) | 1)
struct Seg {
    vi cnt, sum, nums; int n;
    Seg(vi& nums_) {
        nums = nums_; n = SZ(nums);
        cnt.resize(n * 4 + 100);
        sum.resize(n * 4 + 100);
    };
    void up(int k) {
        cnt[k] = cnt[lc(k)] + cnt[rc(k)];
        sum[k] = sum[lc(k)] + sum[rc(k)];
    }
    void modify(int k, int l, int r, int x, int v) {
        if(l == r) {
            cnt[k] += v, sum[k] += nums[l] * v;
            return;
        }
        int mid = l + r >> 1;
        if(x <= mid) modify(lc(k), l, mid, x, v);
        else modify(rc(k), mid + 1, r, x, v);
        up(k);
    }
    void modify(int x, int v) {
        modify(1, 0, SZ(nums) - 1, x, v);
    }
    ll query(int k, int l, int r, int x, int y, int op) {
        if(x <= l && r <= y) return op ? sum[k] : cnt[k];
        int mid = l + r >> 1; ll res = 0;
        if(x <= mid) res += query(lc(k), l, mid, x, y, op);
        if(y > mid) res += query(rc(k), mid + 1, r, x, y, op);
        return res;
    }
    ll queryCnt(int x, int y) {
        return query(1, 0, SZ(nums) - 1, x, y, 0);
    }
    ll querySum(int x, int y) {
        return query(1, 0, SZ(nums) - 1, x, y, 1);
    }
    int find(int k, int l, int r, int p) {
        if(l == r) return l;
        int mid = l + r >> 1;
        if(cnt[lc(k)] < p) return find(rc(k), mid + 1, r, p - cnt[lc(k)]);
        else return find(lc(k), l, mid, p);
    }
    int find(int p) {
        return find(1, 0, SZ(nums) - 1, p);
    }
};

void solve() {
    int n; ll k;
    cin >> n >> k;
    vi a(n + 1), nums;
    for(int i = 1; i <= n; i++) {
        cin >> a[i], a[i] -= i;
        nums.pb(a[i]);
    }
    sort(nums.begin(), nums.end());
    nums.erase(unique(nums.begin(), nums.end()), nums.end());
    Seg seg(nums);
    int ans = 1;
    // for(auto i : nums) cerr << i << ' '; cerr << '\n';
    for(int i = 1; i <= n; i++) {
        // cerr << a[i] << ' ';
        a[i] = lower_bound(nums.begin(), nums.end(), a[i]) - nums.begin();
    }
    // cerr << '\n';
    for(int i = 1, j = 0; i <= n; i++) {
        auto calc = [&]() -> ll {
            int cnt = j - i + 1;
            int val = seg.find((cnt + 1) / 2);
            int cc = seg.queryCnt(0, val);
            ll res = nums[val] * cc - seg.querySum(0, val) +
                    seg.querySum(val + 1, SZ(nums) - 1) - nums[val] * (cnt - cc);
            // cerr << i << ' ' << j << ' ' << val << ' ' << cc << ' ' << res << '\n';
            return res;
        };
        while(j < n) {
            j++; seg.modify(a[j], 1);
            if(calc() > k) {
                seg.modify(a[j], -1); j--; break;
            }
        }
        ans = max(ans, j - i + 1);
        seg.modify(a[i], -1);
    }
    cout << ans << '\n';
}
signed main() {
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    int t = 1;
    cin >> t;
    while(t--) solve();
    return 0;
}