#include <bits/stdc++.h>

using namespace std;
using ll = long long;

struct Point {
    int x, y;
    Point() = default;
    Point(int x, int y) : x(x), y(y) {};
};

struct Option {

    Point A, B;
    Point left_out;

    Option(Point& A, Point& B, Point& left_out) : A(A), B(B), left_out(left_out) {};

    double get_dist(const Point& A, const Point& B) {

        double axis_x = abs(A.x - B.x);
        double axis_y = abs(A.y -  B.y);

        return sqrt(axis_x * axis_x + axis_y * axis_y);
    }


    double get_min_dist() {
        double radius = get_dist(A, B) / 2;

        auto center = [&](const Point& A, const Point& B) {
            int x = (A.x + B.x)/2;
            int y = (A.y + B.y)/2;
            return Point(x, y);
        };

        Point center_pt = center(A, B);

        double center_dist = get_dist(left_out, center_pt);
        return abs(radius - center_dist);
    }
};

void solve() {

    Point A, B, C;
    cin >> A.x >> A.y;
    cin >> B.x >> B.y;
    cin >> C.x >> C.y;

    Option opt_1(A, B, C);
    Option opt_2(A, C, B);
    Option opt_3(C, B, A);

    vector<Option> opts = {opt_1, opt_2, opt_3};

    double min_dist = 1000000;
    for (auto& opt : opts) {
        if (opt.get_min_dist() < min_dist) {
            min_dist = opt.get_min_dist();
        }
    }
    cout << min_dist << '\n';
}


int main() {
    solve();
    return 0;
}