include "stdio.h"
#include <math.h>
#define P 3.141592653589793
main(){
  double a,b,a1,b1,a2,b2,a3,b3,s,R,r,c,zhou;
char aa;
while(scanf("%c",&aa)&&(aa!=EOF))
{
 
scanf("%lf %lf %lf %lf %lf %lf",&a1,&b1,&a2,&b2,&a3,&b3);
a=sqrt(pow((a1-a2),2)+pow((b1-b2),2));
b=sqrt(pow((a1-a3),2)+pow((b1-b3),2)); 
c=sqrt(pow((a2-a3),2)+pow((b3-b2),2));
R=(a+b+c)/2;
s=sqrt(R*(R-a)*(R-b)*(R-c));
r=a*b*c/4/s;
zhou=P*r*2;
printf("%.2lf\n",zhou);  
  
 }

}