#include <iostream>
#include <cmath>

using namespace std;

double d(double ax, double ay, double bx, double by, double cx, double cy)
{
    double dx, dy;
    dx = (ax + bx) / 2;
    dy = (ay + by) / 2;
    double radius = sqrt(pow(ax - bx, 2) + pow(ay - by, 2)) / 2;
    return fabs(sqrt(pow(dx - cx, 2) + pow(dy - cy, 2)) - radius);
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    double ax, ay, bx, by, cx, cy;
    cin >> ax >> ay >> bx >> by >> cx >> cy;

    double out = INFINITY;
    out = min(out, d(ax, ay, bx, by, cx, cy));
    out = min(out, d(ax, ay, cx, cy, bx, by));
    out = min(out, d(cx, cy, bx, by, ax, ay));

    cout.precision(8);
    cout << out << '\n';

    return 0;
}