#include<cstdio>

using namespace std;

int main()
{
	int T, n, c;
	scanf("%d", &T);
	for (int cas = 1; cas <= T; cas++) {
		scanf("%d", &n);
		double sum = 0.0, x;
		for (int i = 0; i < n; i++) {
			scanf("%lf", &x);
			sum += x;
		}
		for (int i = 0; i < n; i++) scanf("%d", &c);
		printf("Case #%d: %.6f\n", cas, (n + 1) / sum);
	}
	return 0;
}