#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long int ull;
typedef long long int ll;
#define int long long
#define fi(i,n) for(int i=0;i<n;i++)
#define f(i, a, b) for(int i=a;i<b;i++)
#define vi vector<int>
#define pb push_back
#define MOD 1000000007
#define pii pair<int, int>
#define ff first
#define ss second
#define setzero(a) memset(a,0,sizeof(a))
#define prDouble(x) cout<<fixed<<setprecision(10)<<x;
#define SetBits(x) __builtin_popcount(x)
#define in_range(x, y, r, c) (x >= 0 && x < r && y >= 0 && y < c)
ll digits(ll n)
{
    return floor(log10(double(n))) + 1;
}
void faster()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
}
ll modularExponentiation(ll x,ll n,ll M)
{
    ll result = 1;
    while(n>0)
    {
        if(n % 2 ==1)
        {
            result = ((result%M)*(x%M))%M;
        }
        x  = ((x%M)*(x%M))%M;
        n = n/2;
    }
    return result%M;
}
bool ispower(int n)
{
    if(n%2==1)
        return false;
    while(n>0)
    {
        if(n%2 == 1)
            return false;
        n = n/2;
    }
    return true;
}

// {1,{2,3}} {2,3}
//4 4

int32_t main()
{
    faster();
    int t;
    cin>>t;
    while(t--)
    {
        int n,m;
        cin>>n>>m;
        int points[n];
        fi(i,n)cin>>points[i];
        vector<int>one_penalty,two_penalty;
        vector<pair<int,pair<int,int>>>dp(2*n + 1);//dp[i] will store max ans till i and penalty
        fi(i,n)
        {
            int x;
            cin>>x;
            if(x==1)
                one_penalty.push_back(points[i]);
            else
                two_penalty.push_back(points[i]);
        }
        int si1 = one_penalty.size();
        int si2 = two_penalty.size();
        sort(one_penalty.begin(),one_penalty.end());
        sort(two_penalty.begin(),two_penalty.end());
        if(si1 - 1>=0)
        {
            dp[1].first = one_penalty[si1 - 1];
            dp[1].second.first = si1 - 2;
            dp[1].second.second = si2 -1;
        }
        else
        {
            dp[1].first = -1;
            dp[1].second.first = -1;
            dp[1].second.second = -1;
        }
        dp[0].first = 0;
        dp[0].second.first = si1 - 1;
        dp[0].second.second = si2 - 1;
        //cout<<dp[1].first<<" ";
        int ans = -1;
        if(dp[1].first>=m)
        {
            ans = 1;
            cout<<ans<<endl;
            continue;
        }
        for(int i = 2; i<=2*n; i++)
        {
            int ma1 = -1;
            int ma2 = -1;
            int pre1 = dp[i - 1].first;
            int pre1first = dp[i - 1].second.first;
            int pre1second = dp[i - 1].second.second;
            //cout<<pre1<<" "<<pre1first<<" "<<pre1second<<endl;
            if(pre1first>=0 && pre1 != -1)
            {
                ma1 = pre1 +one_penalty[pre1first];
            }
            int pre2 = dp[i - 2].first;
            int pre2first = dp[i - 2].second.first;
            int pre2second = dp[i - 2].second.second;
            if(pre2second>=0 && pre2 != -1)
            {
                ma2 = pre2 + two_penalty[pre2second];
            }
            if(ma1 == -1 && ma2 == -1)
            {
                dp[i].first = -1;
                dp[i].second.first = -1;
                dp[i].second.first = -1;
            }
            else if(ma1>ma2)
            {
                dp[i].first = ma1;
                dp[i].second.first = dp[i - 1].second.first - 1;
                dp[i].second.second = dp[i -1].second.second;
            }
            else
            {
                dp[i].first =ma2;
                dp[i].second.first = dp[i - 2].second.first;
                dp[i].second.second = dp[i - 2].second.second - 1;
            }
            //cout<<dp[i].first<<" ";
            if(dp[i].first >= m)
            {
                ans = i;
                break;
            }
            //cout<<dp[i].first<<" ";

        }
        cout<<ans<<endl;

    }
}
