1 //Accepted    1100 KB    0 ms
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 double ab,ac,bc,p;
 6 double slove()
 7 {
 8     p=1/(1+1/p);
 9     return ab*sqrt(p);
10 }
11 int main()
12 {
13     int T;
14     scanf("%d",&T);
15     for (int t=1;t<=T;t++)
16     {
17         scanf("%lf%lf%lf%lf",&ab,&ac,&bc,&p);
18         printf("Case %d: %.9lf\n",t,slove());
19     }
20     return 0;
21 }