#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double db;
typedef pair<ll,ll> P;
#define pb push_back
#define ft first
#define sd second
#define mp make_pair
#define fr(i,n) for(int i=0;i<n;i++)
#define Fr(i,n) for(int i=0;i++<n;)
#define ifr(i,n) for(int i=n-1;i>=0;i--)
#define iFr(i,n) for(int i=n;i>0;i--)

int main(){
  int x[3],y[3];
  db r[3],R,a[3],s,b;
  fr(i,3) cin>>x[i]>>y[i];
  Fr(i,3) a[i-1]=sqrt((x[i%3]-x[i-1])*(x[i%3]-x[i-1])+(y[i%3]-y[i-1])*(y[i%3]-y[i-1]));
  s=(a[0]+a[1]+a[2])/2;
  R=sqrt((s-a[0])*(s-a[1])*(s-a[2])/s);
  b=max(a[0],max(a[1],a[2]));
  printf("%.12f\n",b*R/(b+2*R));
}