#include <bits/stdc++.h>
using namespace std;
const int maxn = 5e5 + 10;
int T, n, a[maxn];
long long k, sum1, sum2;
multiset<int, greater<>> st1;
multiset<int> st2;
inline long long calc() {
  int mid = *st1.begin();
  long long tot = sum2 - 1ll * st2.size() * mid + 1ll * st1.size() * mid - sum1;
  return tot;
}
inline void update() {
  if(st1.size() < st2.size()) {
    int val = *st2.begin();
    st2.erase(st2.begin()), sum2 -= val;
    st1.insert(val), sum1 += val;
  }
  while(!st1.empty() && !st2.empty() && *st1.begin() > *st2.begin()) {
    int val1 = *st1.begin(), val2 = *st2.begin();
    st1.erase(st1.begin()), st2.erase(st2.begin());
    st1.insert(val2), st2.insert(val1);
    sum1 = sum1 - val1 + val2, sum2 = sum2 - val2 + val1;
  }
}
inline void solve() {
  cin >> n >> k, sum1 = sum2 = 0, st1.clear(), st2.clear();
  for(int i = 1; i <= n; ++i) cin >> a[i], a[i] -= i;
//  for(int i = 1; i <= n; ++i) cout << a[i] << ' '; cout << '\n';
  int l = 1, ans = 0;
  for(int i = 1; i <= n; ++i) {
    if(st1.size() <= st2.size()) st1.insert(a[i]), sum1 += a[i];
    else st2.insert(a[i]), sum2 += a[i];
    update();
    while(l < i && calc() > k) {
      if(st1.count(a[l])) st1.extract(a[l]), sum1 -= a[l];
      else st2.extract(a[l]), sum2 -= a[l];
      update(), ++l;
    }
//    cout << l << ' ' << i << ' ' << calc() << '\n';
//    for(auto &x : st1) cout << x << ' ';
//    cout << "| ";
//    for(auto &x : st2) cout << x << ' ';
//    cout << '\n';
    ans = max(ans, i - l + 1);
  }
  cout << ans << '\n';
}
int main() {
  ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
  cin >> T;
  while(T--) solve();
  return 0;
}