#include <iostream>
#include <cstdio>
#include <vector>
#include <cmath>
#include <cstring>
#include <numeric>
#include <algorithm>
#include <functional>
#include <array>
#include <map>
#include <queue>
#include <limits.h>
#include <set>
#include <stack>
#include <random>
#include <complex>
#include <unordered_map>
#define rep(i,s,n) for(int i = (s); (n) > i; i++)
#define REP(i,n) rep(i,0,n)
#define RANGE(x,a,b) ((a) <= (x) && (x) < (b))
#define DUPLE(a,b,c,d) (RANGE(a,c,d) || RANGE(b,c,d) || RANGE(c,a,b) || RANGE(d,a,b))
#define INCLU(a,b,c,d) (RANGE(a,c,d) && (b,c,d))
#define PW(x) ((x)*(x))
#define ALL(x) (x).begin(), (x).end()
#define RALL(x) (x).rbegin(), (x).rend()
#define MODU 1000000007LL
#define bitcheck(a,b)   ((a >> b) & 1)
#define bitset(a,b)      ( a |= (1 << b))
#define bitunset(a,b)    (a &= ~(1 << b))
#define MP(a,b) make_pair((a),(b))
#define Manh(a,b) (abs((a).first-(b).first) + abs((a).second - ((b).second))
#define pritnf printf
#define scnaf scanf
#define itn int
#define PI 3.141592653589


#define izryt bool
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
template<typename A, size_t N, typename T>
void Fill(A(&array)[N], const T &val) {
	std::fill((T*)array, (T*)(array + N), val);
}
pll Dir[8] = { //移動
	{ 0 ,1 },{ -1 ,0 },{ 1 ,0 },{ 0 ,-1 },
	{ 1 ,1 },{ 1 ,-1 },{ -1 ,1 },{ -1 ,-1 }
};

//[a, b)
#define Getsum(ar, a,b) (ar[b] - ar[a])
#define INF 10000000000000000LL

struct Edge {
	int from, to;
	ll w;
};
typedef vector<vector<Edge>> Graph;

ll gcd(ll a, ll b) {
	if (b == 0) return a;
	return gcd(b, a%b);
}
ll lcm(ll m, ll n)
{
	return m * n / gcd(m, n);
}

ll gettugibaisu(ll from, ll k) {

	ll ret = ((from + k - 1) / k) * k;

	return ret;
}

ll getmaebaisu(ll to, ll k) {

	ll ret = (to / k) * k;

	return ret;
}
class Loli {
	char str[601];
	int hash[601], pw[601];
	int mod = 1000000007, base = 1007;
	int len;
public:
	Loli() {};
	
	void setstr(char *str2, int n) {
		strcpy(str,str2);
		len = n;
		hash[0] = 0;
		pw[0] = 1;
		rep(i, 1, len + 1) {
			pw[i] = ((ll)pw[i - 1] * base) % mod;
			hash[i] = ((ll)hash[i - 1] * base + (int)str[i - 1]) % mod;
		}
	}

	inline int gethash(int l, int r) {//半開
		return  (hash[r] - (ll)hash[l] * pw[r - l] % mod + mod) % mod;
	}
};

////テンプレ////
const double EPS = 1e-8;
typedef complex<double> Pt;//点
namespace std {
	bool operator < (const Pt& a, const Pt& b) {
		return real(a) != real(b) ? real(a) < real(b) : imag(a) < imag(b);
	}
}
double distancePP(const Pt &p, const Pt &q) {
	return hypot(p.real() - q.real(), p.imag() - q.imag());
}

double getcosbc(double a, double b, double c) {
	return (b*b + c * c - a * a) / (2 * b * c);
}

signed main(void) {
	double x1, x2, x3, y1, y2, y3;
	Pt p[3];

	cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;

	p[0] = { x1,y1 };
	p[1] = { x2,y2 };
	p[2] = { x3,y3 };
	double Maxr = 0;
	double l[3] = { distancePP(p[0], p[1]),distancePP(p[1], p[2]),distancePP(p[2], p[0]) };
	REP(tei, 3) {
		double a= l[(tei + 2) % 3], b= l[(tei + 1) % 3], c = l[tei];
		double cs[2] = {getcosbc(a,b,c), getcosbc(b,a,c)};
		double s[2] = { acos(cs[0]), acos(cs[1]) };

		double r = c / (2 + 1 / tan(s[0] / 2) + 1 / tan(s[1] / 2));
		Maxr = max(Maxr, r);
	}
	printf("%.12lf\n" ,Maxr);
	return 0;
}



Measured memory_bytes: 256