#include<iostream>
#include <cstdio>
#include<cmath>
using namespace std;
#define pi acos(-1.0)
typedef struct node
{
int x;
int y;
}point;
double AREA(point a, double r1, point b, double r2)
{
double d = sqrt((a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y));
if (d >= r1+r2)
return 0;
if (r1>r2)
{
double tmp = r1;
r1 = r2;
r2 = tmp;
}
if(r2 - r1 >= d)
return pi*r1*r1;
double ang1=acos((r1*r1+d*d-r2*r2)/(2*r1*d));
double ang2=acos((r2*r2+d*d-r1*r1)/(2*r2*d));
return ang1*r1*r1 + ang2*r2*r2 - r1*d*sin(ang1);
}
int main()
{
int t;
scanf("%d", &t);
for(int cas=1; cas<=t; cas++)
{
point a, b; //圆a，b的圆心
int ra, rb; //圆a，b的半径
scanf("%d%d%d%d%d%d", &a.x, &a.y, &ra, &b.x, &b.y, &rb);
printf("Case %d: %.10f\n", cas, AREA(a, ra, b, rb));
}
return 0;
}
详细题目参见：LightOJ——1118
