#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

int main()
{
    cin.tie(0);
    ios_base::sync_with_stdio(0);
    ll z;
    cin>>z;
    while(z--){
        ll n, k;
        cin>>n>>k;
        map<ll, ll> plan;
        priority_queue<ll> pod;
        ll sum=0;
        ll x;
        for(ll i=0; i<n; i++){
            cin>>x;
            sum+=x;
            plan[x]++;
        }
        ll wyn=0;
        while(!plan.empty() && k<sum){
            auto con=plan.upper_bound(k);
            if(con==plan.begin()){
                //cout<<"error";
                wyn=-1;
                break;
            }
            con--;
            ll walka=con->first;
            wyn++;
            k+=walka;
            sum-=walka;
            plan[walka]--;
            if(plan[walka]==0){
                plan.erase(walka);
            }
        }
        cout<<wyn<<'\n';
    }
}