#include <iostream>
#include <cstring>
#include <string>
#include <vector>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <bitset>
using namespace std;
#define maxn 1005
bitset<1100> b[maxn];
int n;
int main()
{
int T;cin>>T;int ca=0;
while(T--){
scanf("%d",&n);
for(int i=1;i<=n;++i) b[i].reset();
for(int i=1;i<=n;++i){
int num;scanf("%d",&num);
b[i][i]=true;
while(num--){
int tmp;
scanf("%d",&tmp);
b[i][tmp]=true;
}
}
for(int i=1;i<=n;++i){
for(int j=1;j<=n;++j){
if(b[j][i]) b[j]|=b[i];
}
}
double ans=0;
for(int i=1;i<=n;++i){
int cnt=0;
for(int j=1;j<=n;++j){
if(b[j][i]) ++cnt;
}
ans+=1.0/cnt;
}
printf("Case #%d: %.5lf
",++ca,ans);
}
return 0;
}