#include <bits/stdc++.h>
using namespace std;

using ll = long long;
const int N = 2e5 + 5;

int n;
ll k;
int w[N];
priority_queue<int> Q;

int main(){
    cin.tie(0);
    ios_base::sync_with_stdio(0);

    int tc=1;
    cin >>tc;
    while(tc--){
        cin >> n >> k;

        for(int i=0;i<n;i++){
            cin >> w[i];
        }

        bool ans = true;
        while(Q.size()) Q.pop();
        int ans2 = 0;

        sort(w,w+n);

        for(int i=0;i<n;i++){
            while(w[i] > k){
                if(!Q.size()){
                    ans = false;
                    break;
                }
                else{
                    k += Q.top(); ans2++;
                    Q.pop();
                }
            }
            Q.push(w[i]);
        }

        if(!ans){
            cout << "-1\n";
        }
        else{
            cout << ans2 << "\n";
        }
    }

    return 0;
}