#include <cstdio>
#include <cmath>
#include <algorithm>
using namespace std;
struct pos { double x, y; };
double dir(pos p1, pos p2) { return sqrt(pow(p1.x - p2.x, 2) + pow(p1.y - p2.y, 2)); }
int main() {
    pos p[3];
    for (int i = 0; i < 3; i++) scanf("%lf %lf%*c", &p[i].x, &p[i].y);
    double a = dir(p[0], p[1]),
        b = dir(p[0], p[2]),
        c = dir(p[1], p[2]),
        s = (a + b + c) / 2.0,
        S = sqrt(s * (s - a) * (s - b) * (s - c)),
        r = 2 * S / (a + b + c),
        D = max(a, max(b, c));
    printf("%.10f\n", r * D / (2 * r + D));
}
