#include <bits/stdc++.h>

using namespace std;

int main()
{
  double x1, y1, x2, y2, x3, y3;
  cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
  double d1 = hypot(x1 - x2, y1 - y2);
  double d2 = hypot(x2 - x3, y2 - y3);
  double d3 = hypot(x3 - x1, y3 - y1);
  double s = (d1 + d2 + d3) * 0.5;
  double S = sqrt(s * (s - d1) * (s - d2) * (s - d3));
  double r = 2 * S / (d1 + d2 + d3);
  auto p = max(d1, max(d2, d3));
  cout << fixed << setprecision(10) << r * p / (p + 2 * r) << endl;
}
