#include <bits/stdc++.h>
using namespace std;

#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define FOR(i, a, b) for (int i = (a); i<(b); ++i)
#define RFOR(i, b, a) for (int i = (b)-1; i>=(a); --i)
#define MP make_pair
#define PB push_back
#define F first
#define S second

typedef long long LL;
typedef pair<int, int> PII;
typedef vector<int> VI;

const int M = 47;
const double alpha = 0.47;

struct Point {
	double x, y;
	Point() {}
	Point(double _x, double _y): x(_x), y(_y) {}
	Point operator+(const Point& p) const {
		return {x + p.x, y + p.y};
	}
	Point operator-(const Point& p) const {
		return {x - p.x, y - p.y};
	}
	Point operator*(double k) const {
		return {k * x, k * y};
	}
	double d2() const {
		return x * x + y * y;
	}
	double len() const {
		return sqrt(d2());
	}
};

double f(const vector<Point>& p, const Point& q) {
	double res = 0;
	FOR(i, 0, 3) {
		res += (q - p[i]).len();
	}
	return res;
}

double f(const vector<Point>& p, double x) {
	double l = -1e4, r = 1e4;
	FOR(i, 0, M) {
		double d = (r - l) * alpha, m1 = l + d, m2 = r - d;
		if (f(p, Point(x, m1)) < f(p, Point(x, m2))) {
			r = m2;
		}
		else {
			l = m1;
		}
	}
	return f(p, Point(x, (l + r) / 2));
}

double f(const vector<Point>& p) {
	double l = -1e4, r = 1e4;
	FOR(i, 0, M) {
		double d = (r - l) * alpha, m1 = l + d, m2 = r - d;
		if (f(p, m1) < f(p, m2)) {
			r = m2;
		}
		else {
			l = m1;
		}
	}
	return f(p, (l + r) / 2);
}

double g(const vector<Point>& p, const Point& q) {
	double res = 0;
	FOR(i, 0, 3) {
		res = max(res, f(vector<Point>{p[i], p[(i + 1) % 3], q}));
	}
	return res;
}

double g(const vector<Point>& p, double x) {
	double l = -1e4, r = 1e4;
	FOR(i, 0, M) {
		double d = (r - l) * alpha, m1 = l + d, m2 = r - d;
		if (g(p, Point(x, m1)) < g(p, Point(x, m2))) {
			r = m2;
		}
		else {
			l = m1;
		}
	}
	return g(p, Point(x, (l + r) / 2));
}

double g(const vector<Point>& p) {
	double l = -1e4, r = 1e4;
	FOR(i, 0, M) {
		double d = (r - l) * alpha, m1 = l + d, m2 = r - d;
		if (g(p, m1) < g(p, m2)) {
			r = m2;
		}
		else {
			l = m1;
		}
	}
	return g(p, (l + r) / 2);
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout << fixed << setprecision(10);
	vector<Point> p(3);
	FOR(i, 0, 3) {
		cin >> p[i].x >> p[i].y;
	}
	cout << g(p) << "\n";
	cerr << (double)clock() / CLOCKS_PER_SEC << endl;
	return 0;
}