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

// 相似 r : r-x -> (r-x)/r -> 1 - x/r
int main(){
    double x[3], y[3];
    for(int i = 0; i < 3; i++)  cin >> x[i] >> y[i];
    double d[3];
    for(int i = 0; i < 3; i++){
        d[i] = sqrt(pow(x[i]-x[(i+1)%3], 2.0)+pow(y[i]-y[(i+1)%3], 2.0));
    }
    double s = (d[0]+d[1]+d[2])/2;
    double area = sqrt(s*(s-d[0])*(s-d[1])*(s-d[2]));
    double r = area/s;
    double ma = *max_element(d, d+3);
    cout << fixed << setprecision(12) << r*ma/(2*r+ma) << endl;
    return 0;
}