#include <bits/stdc++.h>

using namespace std;

using ll = long long;

struct P {
    typedef double T;
    T x, y;
    explicit P(T x=0, T y=0) : x(x), y(y) {}
    P rotate(double a) const {
        return P(x*cos(a)-y*sin(a), x*sin(a)+y*(cos(a)));
    }
    P operator-(P p) {
        return P(x-p.x, y-p.y);
    }
    double angle() const {
        return atan2(y, x);
    }
    T dist2() const {return x*x + y*y;}
    double dist() const {return sqrt((double)dist2());}
};

double ans(P a, P b, P c){
    double r = (b - a).dist() / 2;
    P m = P((a.x + b.x)/2, (a.y + b.y)/2);
    double d = (m-c).dist();
    return abs(r - d);
}

int main() {
    cin.tie(0)->sync_with_stdio(0);

    P a, b, c;
    int x, y; cin >> x >> y; a = P(x, y);
    cin >> x >> y; b = P(x, y);
    cin >> x >> y; c = P(x, y);

    double res = 1e18;
    res = min(res, ans(a, b, c));
    res = min(res, ans(a, c, b));
    res = min(res, ans(b, a, c));
    res = min(res, ans(b, c, a));
    res = min(res, ans(c, a, b));
    res = min(res, ans(c, b, a));

    cout << setprecision(18);
    cout << res << "\n";
}