#include <bits/stdc++.h>
#define endl '\n'
#define int long long
#define gcd __gcd
using namespace std;
typedef pair<int,int> pii;
const int INF = 9e18;
const int inf = 2e9;
const int N = 2e5 + 10;

signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t;
    cin >> t;
    while(t --)
    {
        int n , k;
        cin >> n >> k ;
        vector<int> a(n + 1);
        multiset<int> mi,ma;
        int sumi = 0,suma = 0;
        for(int i = 1;i <= n;i ++) cin >> a[i];
        for(int i = 1;i <= n;i ++) a[i] -= i;
        int ans = 0;
        auto del = [&](int x,int cnt) -> void
        {
            if(x < *ma.begin())
            {
                mi.erase(x);
                sumi -= x;
            }
            else
            {
                ma.erase(x);
                suma -= x;
            }
            while(mi.size() < cnt / 2)
            {
                int t = *ma.begin();
                mi.insert(*ma.begin());
                ma.erase(ma.begin());
                suma -= t;
                sumi += t;
            }
            while(mi.size() > cnt / 2)
            {
                int t = *mi.rbegin();
                ma.insert(*mi.rbegin());
                mi.erase(mi.find(t));
                suma += t;
                sumi -= t;
            }
        };

        auto check = [&](int x,int cnt) -> bool
        {
            if(ma.size() == 0 || x > *ma.begin()) ma.insert(x),suma += x;
            else mi.insert(x),sumi += x;
            while(mi.size() < cnt / 2)
            {
                int t = *ma.begin();
                mi.insert(*ma.begin());
                ma.erase(ma.begin());
                suma -= t;
                sumi += t;
            }
            while(mi.size() > cnt / 2)
            {
                int t = *mi.rbegin();
                ma.insert(*mi.rbegin());
                mi.erase(mi.find(t));
                suma += t;
                sumi -= t;
            }
            int z = *ma.begin();
            int ans = abs(suma - (int)ma.size() * z) + abs(z * (int)mi.size() - sumi);
            // cout << "zz" << z << endl;
            if(ans > k)
            {
                del(x,cnt - 1);
            }

            return ans <= k;
        };

        for(int i = 1,j = 0;i <= n;i ++)
        {
            while(j + 1 <= n && check(a[j+1],j - i + 2)) j ++;
            ans = max(ans,j - i + 1);
            // cout << i << ' ' << j << endl;
            del(a[i],j - i);
        }
        cout << ans << endl;
    }
}