#include<bits/stdc++.h>
using namespace std;
const int N=500+10;
const double eps=1e-8;
int t,c,n,a[N],tot1=0,tot2=0;
double f[N][N];
struct node
{
    double pos,val;
}a1[N],a2[N];
int read()
{
    int s=0,w=1;
    char ch=getchar();
    while(ch<'0'||ch>'9')
    {
        if(ch=='-')
            w=-1;
        ch=getchar();
    }
    while(ch>='0'&&ch<='9')
        s=s*10+(ch-'0'),ch=getchar();
    return s*w;
}
bool cmp1(node a,node b)
{
    if(a.val!=b.val)
        return a.val>b.val;
    else
        return a.pos>b.pos;
}
bool cmp2(node a,node b)
{
    if(a.val!=b.val)
        return a.val<b.val;
    else
        return a.pos<b.pos;
}
double Pos1(int i,double t)
{
    return a1[i].pos+a1[i].val*t;
}
double Pos2(int i,double t)
{
    return a2[i].pos+a2[i].val*t;
}
int main()
{
    t=read();
    for(int T=1;T<=t;++T)
    {
        c=read(),n=read();
        tot1=0,tot2=0;
        for(int i=1;i<=n;++i)
            a[i]=read();
        for(int i=1;i<=n;++i)
        {
            if(a[i]<0)
                a1[++tot1]=(node){1.0*a[i],-1.0*read()};
            else
                a2[++tot2]=(node){1.0*a[i],1.0*read()};
        }
        sort(a1+1,a1+tot1+1,cmp1);
        sort(a2+1,a2+tot2+1,cmp2);
        for(int i=0;i<=tot1;++i)
            for(int j=0;j<=tot2;++j)
                f[i][j]=1e12;
        f[tot1][tot2]=0;
        for(int i=tot1;i>=0;--i)
            for(int j=tot2;j>=0;--j)
            {
                double maxn=0;
                for(int k=tot1;k>=1;--k)
                {
                    double tim=(-Pos1(k,f[i][j]))/(c+a1[k].val);
                    maxn=max(maxn,tim);
                    if(k==1&&j==0)
                        f[k-1][j]=min(f[k-1][j],f[i][j]+maxn);
                    else
                        f[k-1][j]=min(f[k-1][j],f[i][j]+2.0*maxn);
                }
                maxn=0;
                for(int k=tot2;k>=1;--k)
                {
                    double tim=Pos2(k,f[i][j])/(c-a2[k].val);
                    maxn=max(maxn,tim);
                    if(k==1&&i==0)
                        f[i][k-1]=min(f[i][k-1],f[i][j]+maxn);
                    else
                        f[i][k-1]=min(f[i][k-1],f[i][j]+2*maxn);
                }
            }
        printf("Case #%d: %.8lf\n",T,f[0][0]);
    }
    return 0;
}