#include <bits/stdc++.h>

using namespace std;

struct Point {
	double x,y;
	Point operator-(const Point &a) { return {x-a.x,y-a.y}; }
	double norm() { return x*x+y*y; }
	double abs() { return sqrt(norm()); }
};

double f(double a,double b,double c) {
	double s=(a+b+c)/2;
	double S=sqrt(s*(s-a)*(s-b)*(s-c));
	return S/s;
}

int main() {
	Point p[3];
	for(int i=0;i<3;++i) cin >> p[i].x >> p[i].y;
	double a=(p[1]-p[0]).abs(),b=(p[2]-p[1]).abs(),c=(p[0]-p[2]).abs();
	double maxi=max({a,b,c});
	printf("%.12f\n",maxi/(maxi/f(a,b,c)+2));
	
	return 0;
}
