#include<bits/stdc++.h>
using namespace std;
#define int long long
void solve() {
    int n;
    cin >> n;
    int k; cin >> k;
    int aps = 0;
    int a[n + 1]; 
    for(int i = 1; i <= n; i++) cin >> a[i];
    multiset<int> data;
    for (int i=1; i<=n; i++) {
        aps += a[i];
        data.insert(a[i]);
    }
    int cnt = 0;
    int cur = k;


    while(aps > cur) {
        auto it = data.upper_bound(cur);
        //cout <<"->" *it << endl;
        if (it == data.begin()) {
            cout << "-1\n";
            return;
        }
        else {
            it--;
            int val = *it;
            //cout <<"Mobilizing" << val << endl;
            aps -= val;
            data.erase(it);
            cur += val;
            cnt++;
        }
    }

    cout << cnt << "\n";
}
signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    int t;
    cin >> t;
    while(t--) {
        solve();
    }
}