#include<bits/stdc++.h>
using namespace std;
using LL=long long;
#define FOR(i,l,r) for(int i=(l);i<=(r);++i)
#define REP(i,n) FOR(i,0,(n)-1)
#define ssize(x) int(x.size())
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...) cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...) {}
#endif
int main() {
	cin.tie(0)->sync_with_stdio(0);
	int tests;
	cin >> tests;
	REP (test, tests) {
		int n, k;
		cin >> n >> k;
		LL cur = k;
		LL sum = 0;
		multiset<LL> s;
		REP (i, n) {
			int x;
			cin >> x;
			s.emplace(x);
			sum += x;
		}
		int ans = 0;
		while (ssize(s)) {
			if (cur >= sum) {
				break;
			}
			auto ptr = s.upper_bound(cur);
			if (ptr == s.begin()) {
				ans = -1;
				break;
			}
			--ptr;
			sum -= *ptr;
			++ans;
			cur += *ptr;
			s.erase(ptr);
		}
		cout << ans << '\n';
	}
}