#include <iostream>

 #include<cstdio>

 #include<cstring>

 #include<algorithm>

 #include<stdlib.h>

 #include<vector>

 #include<cmath>

 #include<queue>

 #include<set>

 using namespace std;

 #define N 100000

 #define LL long long

 #define INF 0xfffffff

 const double eps = 1e-;

 const double pi = acos(-1.0);

 const double inf = ~0u>>;

 int dcmp(double x)

 {

     if(fabs(x)<eps) return ;

     else return x<?-:;

 }

 int main()

 {

     double a,b,c,l;

     int kk = ;

     while(scanf("%lf%lf%lf%lf",&a,&b,&c,&l)!=EOF)

     {

         if(fabs(a)<eps&&fabs(b)<eps&&fabs(c)<eps&&fabs(l)<eps) break;

         double p = (a+b+c)/;

         double area = sqrt(p*(p-a)*(p-b)*(p-c));

         double r = sqrt((p-a)*(p-b)*(p-c)/p);

         double ans ;

         if(dcmp(*pi*r-l)>=)

         {

             ans = l*l/(*pi);

             //cout<<"2"<<endl;

         }

         else if(dcmp(l-a-b-c)>=)

         {

             ans = area;

             //cout<<"1"<<endl;

         }

         else

         {

             double k = (a+b+c-l)/(a+b+c-*pi*r);

             r*=k;

             ans = area-area*k*k+pi*r*r;

            // cout<<"3"<<endl;

         }

         printf("Case %d: %.2f\n",++kk,ans);

     }

     return ;

 }