#include <iostream>
#include <cmath>
using namespace std;

void Solve(double a, double b, double c, double d, double e, double f)
{
	double ans;
	ans = sqrt((8*c*e*f
	-(a-e-c)*(d-f-e)*(b-c-f)-(a-c-e)*(d-e-f)*(b-f-c)
         -(a-c-e)*(a-c-e)*2*f-(d-f-e)*(d-f-e)*(2*c)
         -(b-f-c)*(b-f-c)*(2*e))/288);
	printf("%.4lf\n", ans);
}

int main()
{
	double a, b, c, d, e, f;
	while (cin>>a>>b>>c>>d>>e>>f)
	{
		Solve(a*a, b*b, c*c, d*d, e*e, f*f);
	}
	return 0;
}