#include <bits/stdc++.h>
#include <cassert>
using namespace std;
using ll = long long;
// #define int ll

template<class T>
struct Point{
    typedef Point P;
    T x, y;
    explicit Point(T x = 0, T y = 0) : x(x), y(y) {}
    T cross(P p) const {return x*p.y - y*p.x;}
    double dist() const {return  sqrt((double)x*x + y*y);}
    P operator-(P p) const {return P(x-p.x, y - p.y);}
    P operator+(P p) const {return P(x+p.x, y + p.y);}

};


signed main() {
    vector<Point<double>> pts(3);
    for (int i = 0; i < 3; i++) {
        cin >> pts[i].x >> pts[i].y;
    }
    double ans = 1e15;
    for (int i = 0; i < 3; i++) {
        for (int j = i + 1; j < 3; j++) {
            for (int z = 0; z < 3; z++) {
                if (z == i || z == j) continue;
                Point mid = pts[i] + pts[j];
                mid.x /= 2;
                mid.y /= 2;
                double mid_dist = (pts[z] - mid).dist();
                double r = (pts[i] - mid).dist();
                ans = min(ans, abs(mid_dist - r));
            }
        }
    }
    cout << fixed << setprecision(10) << ans << endl;

}