#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>

using namespace std;

using i64 = long long;

void solve() {
    int n, k;
    cin >> n >> k;
    vector<i64> a(n + 10), b(n + 10);
    vector<i64> cnt_less(n + 10), cnt_greater(n + 10);
    vector<i64> sum_less(n + 10), sum_greater(n + 10);
    for (int i = 1; i <= n; i++) {
        cin >> a[i];  
        b[i] = a[i] - a[i - 1];
    }
    for (int i = 2; i <= n; i++) {
        cnt_less[i] = cnt_less[i - 1] + (b[i] < 1);
        sum_less[i] = sum_less[i - 1] + (b[i] < 1) * b[i];
        cnt_greater[i] = cnt_greater[i - 1] + (b[i] >= 1);
        sum_greater[i] = sum_greater[i - 1] + (b[i] >= 1) * b[i];
    }
    int l = 0, r = n - 1;
    auto check = [&](int mid) -> bool {
        if (mid == 0) return true;
        for (int l = 2, r = l + mid - 1; r <= n; l++, r++) {
            i64 s = sum_greater[r] - sum_greater[l - 1] + sum_less[r] - sum_less[l - 1];
            i64 need = cnt_less[r] - cnt_less[l - 1] - sum_less[r] + sum_less[l - 1];
            int len = r - l + 1;
            if (s > len) {
                need -= (b[r] < 1);
                need += b[r] * (b[r] < 1);
                need -= (b[l] < 1);
                need += b[l] * (b[l] < 1);
                i64 more = s - len;
                need += more;
                i64 lmore = max(0ll, b[l] - 1);
                i64 x = b[l], y = b[r];
                b[l] -= min(more, lmore);
                more -= min(more, lmore);
                b[r] -= more;
                need += (b[r] < 1);
                need -= b[r] * (b[r] < 1);
                need += (b[l] < 1);
                need -= b[l] * (b[l] < 1);
                b[l] = x, b[r] = y;
            }
            if (s < len) {
                need -= (b[r] < 1);
                need += b[r] * (b[r] < 1);
                need -= (b[l] < 1);
                need += b[l] * (b[l] < 1);
                i64 more = len - s;
                need += more;
                i64 lmore = max(0ll, 1 - b[l]);
                i64 x = b[l], y = b[r];
                b[l] += min(more, lmore);
                more -= min(more, lmore);
                b[r] += more;
                need += (b[r] < 1);
                need -= b[r] * (b[r] < 1);
                need += (b[l] < 1);
                need -= b[l] * (b[l] < 1);
                b[l] = x, b[r] = y;
            }
            if (need <= k) return true;
        }    
        return false;
    };
    while (l < r) {
        int mid = l + r + 1 >> 1;
        if (check(mid)) l = mid;
        else r = mid - 1;
    }
    cout << l + 1 << '\n';
}

int main() {
    cin.tie(0)->sync_with_stdio(false);
    int T;
    cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}