#include<bits/stdc++.h>
using namespace std;
#define time chrono::system_clock::now().time_since_epoch().count()
mt19937_64 rnd(time);
#define maxn 1000005
#define int long long

int read() {int x;cin>>x;return x;}

void solve() {
    int n = read(), k = read();
    vector<int>a(n + 1);
    for(int i = 1; i <= n; i++) {
        a[i] = read();
        a[i] -= i;
    }
    set<pair<int,int>>s1,s2;
    vector<int>f(n + 1);
    int sum1 = 0, sum2 = 0, l = 1;

    auto gao1 = [&]() {
        auto it = s1.end(); it --;
        s1.erase(s1.find(*it));
        // cout << it->fi`rst << "  " << it->second << "!!!\n";
        // cout << "ok!!\n";
        s2.insert(*it);
        f[it -> second] = 2;
        sum1 -= it -> first;
        sum2 += it -> first;
    };
    auto gao2 = [&]() {
        auto it = s2.begin();
        s2.erase(s2.find(*it));
        s1.insert(*it);
        f[it -> second] = 1;
        sum2 -= it -> first;
        sum1 += it -> first;
    };
    int ans = 1;
    for(int r = 1; r <= n; r++) {
        s2.insert({a[r], r});
        f[r] = 2;
        sum2 += a[r];
        // cout << s1.size() << " " << s2.size() << "\n";
        if(s2.size() - s1.size() == 2) {
            gao2();
            // cout << "gao2:" << s2.size() << "\n";
        }
        while(1) {
            // cout << s1.size() << " " << s2.size() << "\n";
            int a1 = sum1;
            int a2 = sum2;
            // cout << a2 << " " << a1 << "\n";
            // cout <<"!!!\n";
            if(s2.size() > s1.size()) {
                a2 -= s2.begin() -> first;
            }
            if(a2 - a1 <= k) { // ok
                break;
            }
            int id = f[l];
            // cout << l << "\n";
            // cout << "r" << r << "\n";
            // cout << "id:" << id << "\n";
            // return;
            if(id == 1) {
                s1.erase({a[l], l});
                sum1 -= a[l];
                l += 1;
                if(s2.size() - s1.size() == 2) gao2();
            }
            else {
                s2.erase({a[l], l});
                sum2 -= a[l];
                l += 1;
                // cout << "!!!>>\n";
                // cout << s1.size() << " " << s2.size() << "\n";
                if(s1.size() > s2.size()) gao1();
                // cout << s1.size() << " " << s2.size() << "\n";
                // cout << s2.begin() ->first << " " << s2.begin() -> second << "\n";
                // cout << "sum :" << sum1 << " " << sum2 << "\n";
                // return;
            }
        }
        // return;
        ans = max(ans, r - l + 1);
    }
    cout << ans << "\n";
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);

    int t = read();
    while(t--) solve();
    return 0;
}