#include<iostream>
#include<cstring>
#include<stdlib.h>
#include<unordered_map>
#include<vector>
#include<array>
#include<math.h>
#include<map>
#include<stdio.h>
#include<queue>
#include<assert.h>
#include<string>
#include<limits.h>
#include<stack>
#include<set>
#include<list>
#include<algorithm>
#include <chrono>
#include<random>
using namespace std;
//
//typedef long long LL;
//#define int long long
//typedef unsigned long long ULL;
//typedef pair<LL, LL>PII;
//typedef pair<double, double>PDD;
//typedef pair<char, char>PCC;
//LL n, m, k;
//
//const LL inf = 1e18;
//const LL N = 1e6 + 10;
//const LL mod = 1e9 + 7;
//const LL mod2 = 998244353;
//
//
//signed main() {
//    std::ios::sync_with_stdio(false);
//    std::cin.tie(nullptr);
//
//    int t = 1;
//    //cin >> t;
//    while (t--) {
//        solve();
//    }
//
//    return 0;
//}


#define int long long
#define MAXN 500000
using namespace std;
int T;
int N, K;
int A[MAXN + 5];
priority_queue<pair<int, int> > q1;
priority_queue<pair<int, int>, vector<pair<int, int> >, greater<pair<int, int> > > q2;
int l = 1, r = 0;
int cnt1 = 0, cnt2 = 0, tmp = 0, sum1 = 0, sum2 = 0, num1 = 0, num2 = 0, ans = 0;
int calc() {
    return (tmp * num1 - sum1) + (sum2 - tmp * num2);
}
void adjust() {
    
    while (num1 < num2&&!q2.empty()) {
        
        pair<int, int> t = q2.top();q2.pop();
        if (t.second < l)continue;
        q1.push(t);
        num1++;
        num2--;
        sum1 += t.first;
        sum2 -= t.first;
        
    }
    while (num1 > num2 + 1&&!q1.empty()) {
        pair<int, int> t = q1.top();q1.pop();
        if (t.second < l)continue;
        q2.push(t);
        num1--;
        num2++;
        sum1 -= t.first;
        sum2 += t.first;
    }
    if (!q1.empty())tmp = q1.top().first;
}
signed main()
{
    //ios::sync_with_stdio(false);
    //cin.tie(0);
    cin >> T;
    while (T--) {
        while (!q1.empty())q1.pop();
        while (!q2.empty())q2.pop();
        cnt1 = 0, cnt2 = 0, tmp = A[1], sum1 = 0, sum2 = 0, num1 = 0, num2 = 0, ans = 0;
        l = 1, r = 0;
        cin >> N >> K;
        for (int i = 1;i <= N;i++) {
            cin >> A[i];
            A[i] -= i;
        }
        for (int i = 1;i <= N;i++) {
            while (l <= r && calc() > K) {
                while (!q2.empty() && q2.top().second < l) {
                    q2.pop();

                }
                while (!q1.empty() && q1.top().second < l) {
                    q1.pop();

                }
                if (A[l] > tmp) {
                    num2--;
                    sum2 -= A[l];
                }
                else {
                    num1--;
                    sum1 -= A[l];
                }
                l++;
                adjust();
            }
            ans = max(ans, num1 + num2);
            if (A[i] > tmp) {
                q2.push(pair<int, int>(A[i], i));

                sum2 += A[i];
                num2++;
            }
            else {
                q1.push(pair<int, int>(A[i], i));

                sum1 += A[i];
                num1++;
            }
            r++;
            adjust();
        }

        while (l <= r && calc() > K) {
            if (A[l] > tmp) {
                num2--;
                sum2 -= A[l];
            }
            else {
                num1--;
                sum1 -= A[l];
            }
            l++;
            adjust();
        }
        ans = max(ans, num1 + num2);

        cout << ans << "\n";
    }
    return 0;
}