/* ***************************************
Author        :Scau.ion
Created Time  :2016/11/28 11:46:06 UTC+8
File Name     :ion.cpp
*************************************** */

#include <bits/stdc++.h>

#define LL long long
#define ULL unsigned long long
#define PB push_back
#define MP make_pair
#define PII pair<int,int>
#define VI vector<int>
#define VPII vector<PII>
#define X first
#define Y second
#define IOS ios::sync_with_stdio(0);cin.tie(0);
#define IN freopen("in", "r", stdin);
#define OUT freopen("out", "w", stdout);

using namespace std;

int main()
{
    double x[3],y[3],len[3];
    for (int j=0;j<3;++j)
        cin>>x[j]>>y[j];
    for (int j=0;j<3;++j)
    {
        double xx=x[j]-x[(j+1)%3];
        double yy=y[j]-y[(j+1)%3];
        len[j]=sqrt(xx*xx+yy*yy);
    }
    double rad[3];
    for (int j=0;j<3;++j)
    {
        double a=len[j],b=len[(j+1)%3],c=len[(j+2)%3];
        rad[j]=acos((b*b+c*c-a*a)/(2*b*c));
        rad[j]/=2;
    }
    double ma=0;
    for (int j=0;j<3;++j)
    {
        double a=tan(rad[(j+1)%3]),b=tan(rad[(j+2)%3]);
        double xi=(len[j]*a*b)/(a+b+a*b*2);
        ma=max(ma,xi);
    }
    printf("%.12lf\n",ma);
    return 0;
}
