#include<bits/stdc++.h>
using namespace std;
#include<ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
typedef tree<
int,
null_type,
less_equal<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;
#define ll long long
#define pb push_back
#define mk make_pair
#define S second
#define F first

map<int, int> mp;
vector<int> t[2];
int n, k;
void upd(int v, int tl, int tr, int pos, int val, int psda){
  if(tl == tr) t[psda][v] += val;
  else {
       int tm = (tl + tr)/2;
       if(pos <= tm) upd(2 * v, tl, tm , pos, val, psda);
       else upd(2 * v + 1, tm + 1, tr, pos, val, psda);
       t[0][v] = t[0][2 * v] + t[0][2 * v + 1];
       t[1][v] = t[1][2 * v] + t[1][2 * v + 1];
  }
}

int get(int v, int tl, int tr, int l, int r, int psda){
    if(l > r) return 0;
    if(l == tl && r == tr) return t[psda][v];
    int tm = (tl + tr)/2;
    return get(2 *v, tl, tm, l, min(tm, r), psda) +
           get(2 *v + 1, tm + 1, tr, max(tm + 1, l), r, psda);
}



void add(int val){
     int i = mp[val];
    // cout << "adding :" << i << " " << val << endl;
     upd(1, 0, n - 1, i, val, 0);
     upd(1, 0, n - 1, i, 1, 1);
}

void del(int val){
     int i = mp[val];
     upd(1, 0, n - 1, i, -val, 0);
     upd(1, 0, n - 1, i, -1, 1);
}

void solve(){
    cin >> n >> k;
    mp.clear();
    t[0].assign(4 * n + 5, 0);
    t[1].assign(4 * n + 5, 0);
    vector<int> v(n);
    ordered_set s;
    for(auto &i : v) cin >> i;

    for(int i = 0; i < n; i++) v[i] -= i, mp[v[i]]++;
    int index = 0;
    for(auto it : mp){
        mp[it.first] = index;
        index++;
    }

    int l = 0;
    int ans = 1;
    for(int r = 0; r < n; r++){
         s.insert(v[r]);
         add(v[r]);
         while(l <= r){
            int le=(r-l+1);
            int med=*s.find_by_order(le/2);
            //cout << "med :" << med << endl;
            int sum1 = get(1, 0, n - 1, 0, mp[med], 0);
            int sum2 = get(1, 0, n - 1, mp[med] + 1, n - 1, 0);

            int cnt1 = get(1, 0, n - 1, 0, mp[med], 1);
            int cnt2 = get(1, 0, n - 1, mp[med] + 1, n - 1, 1);
            int cost = cnt1 * med - sum1 + sum2 - cnt2 * med;
           // cout << l << " " << r << " " << sum1 << " " << sum2 << " " << cost << '\n';
            if(cost <= k){
                 ans = max(ans, r - l + 1);
                 break;
            }

            s.erase(s.upper_bound(v[l]));
            del(v[l]);
            l++;
         }
      }
      cout << ans << '\n';
}
int main(){
   ios::sync_with_stdio(0); cin.tie(NULL); cout.tie(NULL);
   int t; cin >> t; while(t--) solve();
}