#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
int n;
long long k,a[N];
multiset<int> S1,S2;
inline void work() {
	cin >> n >> k;
	for(int i = 1;i <= n;i++) cin >> a[i];
	S1.clear(),S2.clear();
	int ans = 0;
	for(int i = 1;i <= n;i++) S1.insert(a[i]);
	while(S1.size()) {
		if(k >= *S1.begin()) {
			auto it = S1.upper_bound(k);
			--it;
			// printf("zhan:%d\n",*it);
			k -= *it;S2.insert(*it);S1.erase(it);
		} else if(S2.size()) {
			k += 2 * (*S2.rbegin());
			S2.erase(prev(S2.end()));
			++ans;
		} else break;
	}
	if(S1.size()) cout << -1 << endl;
	else cout << ans << endl;
}
int main() {
	int T;
	cin >> T;
	while(T--) work();
	return 0;
}