#include<bits/stdc++.h>
using namespace std;
template <typename T> inline void read(T &x)
{
	x=0;short f=1;char c=getchar();
	for(;c<'0'||c>'9';c=getchar()) if(c=='-') f=-1;
	for(;c>='0'&&c<='9';c=getchar()) x=(x<<1)+(x<<3)+(c^48);
	x*=f;return;
}
#define ll long long
int n,k;
multiset<int>S;
int main()
{
	int T;read(T);
	while(T--)
	{
		read(n),read(k);
		S.clear();
		ll sum=0;
		for(int i=1,x;i<=n;++i)
			read(x),sum+=x,S.insert(x);
		int ans=0;
		while(S.size()&&sum>k)
		{
			auto it=S.lower_bound(k);
			if(it==S.end()) it=prev(it);
			if(*it>k)
			{
				if(it!=S.begin()) it=prev(it);
				else break;
			}
			if(*it>k) break;
			ll x=*it;
			k+=x,sum-=x,++ans;
			S.erase(it);
		} 
		if(sum>k) puts("-1");
		else printf("%d\n",ans);
	}
}