> //V=sqrt((4*a*a*b*b*c*c-a*a*(b*b+c*c-m*m)*(b*b+c*c-m*m)-b*b*(c*c+a*a-n*n)*(c*c+a*a-n*n)-c*c*(a*a+b*b-l*l)*(a*a+b*b-l*l)+(a*a+b*b-l*l)*(b*b+c*c-m*m)*(c*c+a*a-n*n)))/12
> //a=AB,b=AC,c=AD,l=BC,m=BD,n=CD;
> #include<stdio.h>
> #include<math.h>
> int main()
> {
>  double a,b,c,l,m,n;
>  double V;
>  while(scanf("%lf%lf%lf%lf%lf%lf",&a,&b,&c,&l,&m,&n)!=EOF)
>  {
>  V=pow(4*a*a*b*b*c*c-a*a*(b*b+c*c-m*m)*(b*b+c*c-m*m)-b*b*(c*c+a*a-n*n)*(c*c+a*a-n*n)-c*c*(a*a+b*b-l*l)*(a*a+b*b-l*l)+(a*a+b*b-l*l)*(b*b+c*c-m*m)*(c*c+a*a-n*n),0.50000);
>  V/=12.0;
>  printf("%.20lf\n",V);
>  }
>  
> }