#include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define x first
#define y second
#define endl '\n'
#define int long long
using namespace std;
using i64 = long long;


bool muti_test = true;


void init() {}


void solve() {
    int n, m;
    cin >> n >> m;
    vector<int>a(n + 1);
    for(int i = 1; i <= n; i++){
        cin >> a[i];
        a[i] -= i;
    }    
    map<int, int>s[3];
    int sz[3] = {0};
    int sum[3] = {0};

    // from i to j
    auto mov=[&](int i, int j, int item){
        sz[i]--;
        sz[j]++;
        s[i][item]--;
        s[j][item]++;
        sum[i] -= item;
        sum[j] += item;
        if(s[i][item] == 0){
            s[i].erase(item);
        }
    };

    auto calc=[&](int l, int r)->int{
        if(l >= r) return 0;
        int mid1 = s[1].end()->first;
        int mid2 = s[2].begin()->first;
        int res1 = mid1 * sz[1] - sum[1] + sum[2] - mid1 * sz[2];
        int res2 = mid2 * sz[1] - sum[1] + sum[2] - mid2 * sz[2];
        return min(res1, res2);
    };
    int ans = 1;
    int l = 1, r = 1;
    while(r <= n){
        sz[2]++;
        sum[2] += a[r];
        s[2][a[r]]++;
        if(sz[2] - sz[1] == 2) mov(2, 1, s[2].begin()->first);
        while(calc(l, r) > m){
            if(s[1][a[l]] > 0){
                s[1][a[l]]--;
                if(!s[1][a[l]]){
                    s[1].erase(a[l]);
                }
                sz[1]--;
                sum[1] -= a[l];
            }else{
                s[2][a[l]]--;
                if(!s[2][a[l]]){
                    s[2].erase(a[l]);
                }
                sz[2]--;
                sum[2] -= a[l];
            }
            l++;
            if(sz[2] - sz[1] == 2) mov(2, 1, s[2].begin()->first);
            else if(sz[1] - sz[2] == 2) mov(1, 2, s[1].end()->first);
        }
        ans = max(ans, r - l + 1);
        r++;
    }
    cout << ans << '\n';
}



signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    init();
    int T = 1;
    if (muti_test)
        cin >> T;
    while (T -- ) {
            solve();
    }
    return 0;
}