#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef int _loop_int;
#define REP(i,n) for(_loop_int i=0;i<(_loop_int)(n);++i)
#define FOR(i,a,b) for(_loop_int i=(_loop_int)(a);i<(_loop_int)(b);++i)
#define FORR(i,a,b) for(_loop_int i=(_loop_int)(b)-1;i>=(_loop_int)(a);--i)
#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl
#define ALL(a) (a).begin(),(a).end()
#define CHMIN(a,b) a=min((a),(b))
#define CHMAX(a,b) a=max((a),(b))
// mod
const ll MOD = 1000000007ll;
#define FIX(a) ((a)%MOD+MOD)%MOD
// floating
typedef double Real;
const Real EPS = 1e-11;
#define EQ0(x) (abs(x)<EPS)
#define EQ(a,b) (abs(a-b)<EPS)
typedef complex<Real> P;
Real calc(P a,P b,P c){
// sub c
a -= c;
b -= c;
// rotate
P rot = b / abs(b);
a /= rot;
b /= rot;
Real mul = b.real();
a /= mul;
if(a.imag()<0){
a = conj(a);
}
// (0,0), (1,0), (x,y>0)
Real p = abs(a);
Real q = abs(a-P(1,0));
Real y = a.imag();
Real s = y/2.0;
Real r = s / (p/2.0 + q/2.0 + y + 0.5);
return r*mul;
}
int main(){
int x,y;
P a,b,c;
scanf("%d%d",&x,&y);a=P(x,y);
scanf("%d%d",&x,&y);b=P(x,y);
scanf("%d%d",&x,&y);c=P(x,y);
Real ans = 0.0;
CHMAX(ans,calc(a,b,c));
CHMAX(ans,calc(b,c,a));
CHMAX(ans,calc(c,a,b));
printf("%.9lf\n",ans);
return 0;
}