#include <algorithm>
#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

int main()
{
    double x[3], y[3];
    double a[3];
    for(int i = 0; i < 3; i++) cin >> x[i] >> y[i];
    for(int i = 0; i < 3; i++)
        a[i] = sqrt((x[(i + 1) % 3] - x[(i + 2) % 3]) * (x[(i + 1) % 3] - x[(i + 2) % 3]) +
                    (y[(i + 1) % 3] - y[(i + 2) % 3]) * (y[(i + 1) % 3] - y[(i + 2) % 3]));
    double c[3];
    for(int i = 0; i < 3; i++)
        c[i] = (a[(i + 1) % 3] * a[(i + 1) % 3] + a[(i + 2) % 3] * a[(i + 2) % 3] - a[i] * a[i]) /
               (2 * a[(i + 1) % 3] * a[(i + 2) % 3]);
    sort(a, a + 3, greater<double>());
    sort(c, c + 3, greater<double>());
    double l = a[0];
    double t0 = sqrt(2 / (c[0] + 1) - 1);
    double t1 = sqrt(2 / (c[1] + 1) - 1);
    cout << fixed << setprecision(15) << (t0 * t1 * l) / (t0 + t1 + 2 * t0 * t1) << endl;
}