#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(a, b) for(int a = 0; a < (b); ++a)
#define st first
#define nd second
#define pb push_back
#define all(a) a.begin(), a.end()
const int LIM=2e5+7;
ll T[LIM];
void solve() {
	ll n, k;
	cin >> n >> k;
	rep(i, n) cin >> T[i];
	sort(T, T+n);
	ll ans=0, l=0, sum=0;
	priority_queue<ll>q;
	while(true) {
		while(l<n && k>=T[l]) {
			q.push(T[l]);
			sum+=T[l];
			++l;
		}
		if(q.empty()) {
			if(l<n) {
				cout << -1 << '\n';
				return;
			}
			break;
		}
		ll p=q.top(); q.pop();
		sum-=p;
		k-=p;
		if(l<n || k<sum) {
			k+=2*p;
			++ans;
		}
	}
	cout << ans << '\n';
}
int main() {
	ios_base::sync_with_stdio(0); cin.tie(0);
	int _=1;
	cin >> _;
	while(_--) solve();
}