#include <bits/stdc++.h>
#include <cassert>
#include <functional>
#include <iterator>
#include <queue>
#include <vector>

#ifdef DYNAMIC_PIGEON
#include "algo/debug.h"
#else
#define debug(...) 114514
#endif

#define Dynamic_Pigeon 0

using i64 = std::int64_t;
using u64 = std::uint64_t;
using u32 = std::uint32_t;

constexpr i64 MOD = i64(1e9) + 7;
constexpr int INF = 1e9;
constexpr i64 INF_LONG_LONG = 1e18;

#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()

template <class C>
struct Q {
  std::priority_queue<int, std::vector<int>, C> q1, q2;
  int size = 0;
  i64 sum = 0;

  void insert(int x) {
    size += 1;
    q1.push(x);
    sum += x;
  }

  void erase(int x) {
    size -= 1;
    q2.push(x);
    sum -= x;
    while (!q2.empty() && q1.top () == q2.top()) {
      q1.pop();
      q2.pop();
    }
  }

  int top() {
    return q1.top();
  }

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

struct Node {
  Q<std::less<int>> l;
  Q<std::greater<int>> r;

  i64 pre() {
    return l.sum;
  }

  i64 lst() {
    return r.sum;
  }

  int get_mid() {
    return l.top();
  }

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

    if (r.size + 1 < l.size) {
      r.insert(l.top());
      l.erase(l.top());
    }

    if (l.size < r.size) {
      l.insert(r.top());
      r.erase(r.top());
    }
  }

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

    if (r.size + 1 < l.size) {
      r.insert(l.top());
      l.erase(l.top());
    }

    if (l.size < r.size) {
      l.insert(r.top());
      r.erase(r.top());
    }
  }
};


void tizzytyt_SuKi() {
  int n;
  i64 k;
  std::cin >> n >> k;
  std::vector<int> a(n + 1);
  for (int i = 1; i <= n; i++) {
    std::cin >> a[i];
    a[i] -= i;
  }

  

  auto check = [&](int len) -> bool {
    Node m;
    for (int i = 1; i < len; i++) {
      m.insert(a[i]);
    }

    i64 res = INF_LONG_LONG;

    for (int i = len; i <= n; i++) {
      m.insert(a[i]);
      i64 mid = m.get_mid();
      i64 p = mid * (len & 1) + m.lst() - m.pre();

      res = std::min(res, p);

      m.erase(a[i - len + 1]);
    }
    return res <= k;
  };

  int l = 1, r = n;
  while (l < r) {
    int mid = (l + r + 1) >> 1;
    if (check(mid)) {
      l = mid;
    } else {
      r = mid - 1;
    }
  }
  std::cout << l << "\n";
}

signed main() {
#ifdef DYNAMIC_PIGEON
  freopen("input.in", "r", stdin);
#else
  std::cin.tie(0)->sync_with_stdio(0);
#endif
  int t = 1;
  std::cin >> t;
  while (t--) {
    tizzytyt_SuKi();
  }
  return Dynamic_Pigeon;
}