#include <bits/stdc++.h>
using namespace std;
// Speed
#define fast_io ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
// Typedefs
#define int long long
#define pb push_back
#define ff first
#define ss second
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) ((int)(x).size())
#define endl '\n'
#define yes cout << "yes\n"
#define no cout << "no\n"
// Loops
#define rep(i,a,b) for(int i=a;i<b;++i)
#define per(i,a,b) for(int i=b-1;i>=a;--i)
#define each(x, a) for (auto& x : a)
// Consts
const int INF = 1e18;
const int MOD = 1e9+7;
const int N = 2e5 + 5;
// Logic
void solve() {
int n;
int k;
cin >> n >> k;
vector<int> q(n);
rep(i, 0, n) cin >> q[i];
vector<int> r(n);
rep(i, 0, n) cin >> r[i];
// Sort q descending: process hardest constraints first
sort(all(q), greater<int>());
// Sort r ascending: incrementally add valid r's
sort(all(r));
int r_ptr = 0;
int ans = 0;
vector<int> valid_r; // Acts as a stack
each(val_q, q) {
// Condition: (val_q + 1) * (val_r + 1) <= k + 1
// val_r <= (k + 1) / (val_q + 1) - 1
int limit = (k + 1) / (val_q + 1) - 1;
// Add all r's that satisfy the condition for the current (and subsequent) q
while (r_ptr < n && r[r_ptr] <= limit) {
valid_r.pb(r[r_ptr]);
r_ptr++;
}
// Match current q with an available r
if (!valid_r.empty()) {
valid_r.pop_back();
ans++;
}
}
cout << ans << endl;
}
// Main
int32_t main() {
fast_io;
int t;
cin >> t;
while (t--) {
solve();
}
return 0;
}
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