#include <bits/stdc++.h>
#define int long long
using namespace std;

struct Node {
    multiset<int> S ; 
    int sum = 0 ; 
    int min() { return *S.begin() ; }
    int size() {
        return S.size() ; 
    }
    void push(int x) {
        sum += x , S.insert(x) ;
    }
    int erase(int m) {
        S.erase(S.find(m)) ; 
        sum -= m ; 
        return m ; 
    }
    int pop_max() {
        return erase(*prev(S.end())) ;
    }
    int pop_min() {
        return erase(*S.begin()) ;
    }
};

int n , K ; 
void solve() {
    cin >> n >> K ;
    vector a(n , 0ll) ; 
    for (auto &i : a) cin >> i ; 
    for (int i = 0 ; i < n ; ++ i) {
        a[i] -= i ; 
    }

    auto check = [&](int len) -> bool {
        Node L , R ; 
        int sl = 0 , sr = 0 ; 
        for (int i = 0 ; i < len ; ++ i) {
            L.push(a[i]) ; 
        }
        while (L.size() > R.size()) {
            R.push(L.pop_max()) ; 
        } // L <= R
        int mid = R.min() ; 
        int tot = (L.size() * mid - L.sum) + (R.sum - R.size() * mid) ; 
        if (tot <= K) return 1 ; 

        for (int i = len ; i < n ; ++ i) {

            if (a[i - len] < R.min()) L.erase(a[i - len]) ;
            else R.erase(a[i - len]) ;
            if (a[i] <= R.min()) L.push(a[i]) ; 
            else R.push(a[i]) ;
            
            while (L.size() > R.size()) R.push(L.pop_max()) ;
            while (R.size() > 1 + L.size()) L.push(R.pop_min()) ; 
            // cout << i << ' ' << L.sum << ' ' << R.sum << '\n' ; 

            // cout << L.size() << ' ' << R.size() << '\n' ;
            int mid = R.min() ; 
            int tot = (L.size() * mid - L.sum) + (R.sum - R.size() * mid) ; 
            if (tot <= K) return 1 ; 
        }
        return 0 ; 
    };  
    // for (int i = 4 ; i <= 4 ; ++ i) {
    //     // cout << i << ' ' << check(i) << '\n' ; 
    //     check(i) ;
    // }
    int l = 1 , r = n ; 
    while (l < r) {
        int mid = l + r + 1 >> 1 ;
        if (check(mid)) l = mid ; 
        else r = mid - 1 ;
    }
    cout << l << '\n' ; 
}
signed main() {
    ios::sync_with_stdio(false) ; 
    cin.tie(0) , cout.tie(0) ; 
    int t;
    cin>>t;
    while(t--) solve();
    return 0;
}