#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define SZ(x) ((int)x.size())
#define rep(i,a,n) for(int i=a;i<n;i++)
#define per(i,a,n) for(int i=n-1;i>=a;i--)
#define IOS ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
using namespace std;
using ll = long long;
using PII = pair<int,int>;
using pll = pair<ll,ll>;
using db = long double;
const int N = 2010,M = 31,mod = 998244353;
const int inf = 1 << 30;

void solve(){
    int n;
    ll k;
    cin >> n >> k;
    vector<int> a(n + 1);
    rep(i,1,n + 1) {
        cin >> a[i];
        a[i] -= i;
    }
    int cnt = 0,ans = 0;
    ll s1 = 0,s2 = 0;
    multiset<int,greater<int>> h1;
    multiset<int> h2;
    auto ins = [&](int x){
        cnt++;
        int m = (cnt + 1) / 2;
        h2.insert(a[x]);
        s2 += a[x];
        while (SZ(h1) < m){
            int y = *h2.begin();
            s1 += y;
            h1.insert(y);
            s2 -= y;
            h2.extract(y);
        }
        while (SZ(h2) && *h1.begin() > *h2.begin()){
            int y = *h1.begin(), z = *h2.begin();
            h1.extract(y);
            s1 += z - y;
            h1.insert(z);
            h2.extract(z);
            h2.insert(y);
            s2 += y - z;
        }
        ll t = s2 - s1 + cnt % 2 * (*h1.begin());
        return t <= k;
    };
    auto era = [&](int x){
        cnt--;
        if (h1.count(a[x])) {
            s1 -= a[x];
            h1.extract(a[x]);
        }
        else {
            h2.extract(a[x]);
            s2 -= a[x];
        }
    };
    for (int i = 1,j = 1;i <= n;i++){
        while (j <= n && ins(j)){
            // cout << i <<  ' ' << j << ' ' << s1 << ' ' << s2 << endl;
            j++;
        }
        // cout << i << ' ' << j << ' ' << s1 << ' ' << s2 << endl;
        if (j <= n) era(j);
        ans = max(ans,cnt);
        era(i);
    }
    cout << ans << "\n";
}

int main(){
    // freopen("input.txt","r",stdin);
    // freopen("3.txt","w",stdout);
    IOS
    int t;
    cin >> t;
    while (t--) solve();
    return 0;
}