#include <bits/stdc++.h>
using namespace std;

int main() {

    pair<double, double> a, b, c;
    scanf("%lf %lf %lf %lf %lf %lf", &a.first, &a.second, &b.first, &b.second, &c.first, &c.second);


    double mi = 1e9;

    pair<double, double> ab = {(a.first + b.first) / 2.0, (a.second + b.second) / 2.0};
    double abd = hypot(a.first - b.first, a.second - b.second);
    pair<double, double> ac = {(a.first + c.first) / 2.0, (a.second + c.second) / 2.0};
    double acd = hypot(a.first - c.first, a.second - c.second);
    pair<double, double> bc = {(b.first + c.first) / 2.0, (b.second + c.second) / 2.0};
    double bcd = hypot(b.first - c.first, b.second - c.second);


    mi = min(mi, abs(hypot(ab.first - c.first, ab.second - c.second) - (abd / 2.0)));
    mi = min(mi, abs(hypot(ac.first - b.first, ac.second - b.second) - (acd / 2.0)));
    mi = min(mi, abs(hypot(bc.first - a.first, bc.second - a.second) - (bcd / 2.0)));

    printf("%lf\n", mi);

    return 0;
}