#include<bits/stdc++.h>
using namespace std;
inline long long read()
{
    long long x=0,flag=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')flag=-flag;ch=getchar();}
    while(ch<='9'&&ch>='0'){x=x*10+ch-'0';ch=getchar();}
    return flag*x;
}
const int b=RAND_MAX;
struct jgt{long long a,b;}a[3005];
bool cmp(jgt x,jgt y){return x.a-x.b<y.a-y.b;}
int ran(int l,int r){return rand()%(r-l+1)+1;}
const double del=0.9765,eps=1e-8;
long long suma,sumb;__int128 ans,C;
int c[3005],n;
void mnth(double T)
{
    while(T>eps)
    {
        int x=ran(1,n);
        if(c[x]) c[x]=0,suma-=a[x].a,sumb+=a[x].b;
        else c[x]=1,suma+=a[x].a,sumb-=a[x].b;
        __int128 now=(__int128)suma*sumb;
        if(now>ans) ans=now;
        else
        {
            double tmp=exp(((now-ans)/C)/T);
            if(rand()>1.0*tmp*b)
            if(c[x]) c[x]=0,suma-=a[x].a,sumb+=a[x].b;
            else c[x]=1,suma+=a[x].a,sumb-=a[x].b;
        }
        T*=del;
    }
}
void print(__int128 x)
{if(!x) return;print(x/10);putchar('0'+(int)x%10);}
int main()
{
    int tim,A,B;cin>>tim;
    cin>>n>>A>>B;C=((__int128)n*A*n*B/4);
    while(tim--)
    {
        long long sb=0;int id=0;
        for(int i=1;i<=n;i++) a[i].a=read();
        for(int i=1;i<=n;i++) a[i].b=read(),sb+=a[i].b;
        sort(a+1,a+n+1,cmp);
        suma=0,sumb=0;ans=0;
        for(int i=1;i<=n;i++)
        {
            suma+=a[i].a;sumb+=a[i].b;
            if((__int128)suma*(sb-sumb)>ans)
            ans=(__int128)suma*(sb-sumb),id=i;
        }
        suma=0;sumb=sb;
        for(int i=1;i<=id;i++)
        c[i]=1,suma+=a[i].a,sumb-=a[i].b;
        for(int i=1;i<=5;i++) mnth(1);
        print(ans);puts("");
    }
    return 0;
}