#include<bits/stdc++.h>
using namespace std;
#define all(vec) vec.begin(),vec.end()
typedef long long int ll;
typedef pair<int,int> P;
typedef pair<P,P> PP;
const ll MOD=10000;
const ll INF=1000000010;
const int MAX=100001;
int dx[8]={0,1,0,-1,1,-1,1,-1};
int dy[8]={1,0,-1,0,1,-1,-1,1};
double dist(double x1,double y1,double x2,double y2){
	return sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
}
int main(){
	double x[3],y[3];
	for(int i=0;i<3;i++){
		cin>>x[i]>>y[i];
	}
	double d[3];
	double ma=0;
	for(int i=0;i<3;i++){
		d[i]=dist(x[i],y[i],x[(i+1)%3],y[(i+1)%3]);
		ma=max(d[i],ma);
	}
	double ss=(d[0]+d[1]+d[2])/2.0;
	double s=sqrt(ss*(ss-d[0])*(ss-d[1])*(ss-d[2]));
	double r=2.0*s/(d[0]+d[1]+d[2]);
	double ok=0.0;double ng=100010.0;
	int c=10000;
	while(c--){
		double mid=(ok+ng)/2;
		if((1-mid/r)*ma>=2*mid){
			ok=mid;
		}else{
			ng=mid;
		}
	}
	printf("%.12f\n",ok);
	return 0;
}
