#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int Mod=1e9+7;
const ll INF = 10000000000000;
const int N = 1e6+7;
 
    void solve() {
        ll n,k;
        cin >> n >> k;
        vector<ll> a(n);
        for(int i=0;i<n;i++) cin >> a[i];
        sort(a.begin(),a.end());
        ll prev=0;
        ll ans =k;
        for(int i=0;i<n && k>0;++i){
            k-=(a[i]-prev)*(n-i);
            prev=a[i];
            ans++;
        }
        cout << ans-1 << '\n';
      }       
 
int main(){ 
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
 
    int t;
    cin >> t;
    while (t--) solve();
 
    return 0;
}
 

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5
2 1
1 1
2 2
1 2
3 4
2 1 3
10 50
1 1 3 8 8 9 12 13 27 27
2 1000000000
1000000000 500000000