#include<bits/stdc++.h>
#define MAXN (505)
#define ll long long
#define db double
#define ldb long double
#define pi pair<int,int>
#define fi first
#define se second
using namespace std;
const int lim=500000;
const ldb eps=1e-12,inf=1e18;
template<typename type>
void read(type &x)
{
    bool f=0;char ch=0;x=0;
    while(ch<'0'||ch>'9'){f|=!(ch^'-');ch=getchar();}
    while(ch>='0'&&ch<='9'){x=(x<<3)+(x<<1)+(ch^48);ch=getchar();}
    x=f?-x:x;
}
template<typename type,typename... Args>
void read(type &x,Args &... args)
{
    read(x);
    read(args...);
}
int test,vt,n,tota,totb,cas;
int pos[MAXN],v[MAXN];
ldb f[MAXN][MAXN];
struct node{
    int pos,vc;
    inline bool operator<(node rsh){return (vc^rsh.vc)?(vc<rsh.vc):(pos<rsh.pos);}
}a[MAXN],b[MAXN];
inline ldb getpos(node x,ldb tim){return x.pos+tim*x.vc;}
inline ldb gettim(node x,ldb tim){return getpos(x,tim)/(vt-x.vc);}
void solve()
{
    read(vt,n);
    for(int i=1;i<=n;i++) read(pos[i]);
    for(int i=1;i<=n;i++) read(v[i]);
    tota=totb=0;
    for(int i=1;i<=n;i++)
    {
        if(pos[i]<0) a[++tota]={-pos[i],v[i]};
        else b[++totb]={pos[i],v[i]};
    }
    sort(a+1,a+tota+1),sort(b+1,b+totb+1);
    for(int i=0;i<=tota;i++) fill(f[i],f[i]+totb+1,inf);
    f[tota][totb]=0;
    for(int i=tota;~i;i--)
    {
        for(int j=tota;~j;j--)
        {
            ldb t=f[i][j],pos1=getpos(a[i],t),pos2=getpos(b[j],t),mx=0;
            for(int k=i;k;k--)
            {
                if(pos1-getpos(a[k],t)<=eps) mx=max(mx,gettim(a[k],t));
                ldb ntim=t+mx*2;
                if(k==1&&!j) ntim-=mx;
                f[k-1][j]=min(f[k-1][j],ntim);
            }
            mx=0;
            for(int k=j;k;k--)
            {
                if(pos2-getpos(b[k],t)<=eps) mx=max(mx,gettim(b[k],t));
                ldb ntim=t+mx*2;
                if(k==1&&!i) ntim-=mx;
                f[i][k-1]=min(f[i][k-1],ntim);
            }
        }
    }
    printf("Case #%d: %.10Lf\n",++cas,f[0][0]);
}
int main()
{
#ifndef ONLINE_JUDGE
    freopen("tiii.in","r",stdin);
    freopen("tiii.out","w",stdout);
#endif
    read(test);
    for(int i=1;i<=test;i++) solve();
}