/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author RiaD
 */

#include <iostream>
#include <fstream>

#include <iostream>


#include <cmath>
#include <tuple>


#include <string>
#include <stdexcept>

#ifndef SPCPPL_ASSERT
	#ifdef SPCPPL_DEBUG
		#define SPCPPL_ASSERT(condition) \
		if(!(condition)) { \
			throw std::runtime_error(std::string() + #condition + " in line " + std::to_string(__LINE__) + " in " + __PRETTY_FUNCTION__); \
		}
	#else
		#define SPCPPL_ASSERT(condition)
	#endif
#endif



template <typename T, typename SquareT = T>
struct Point2D {
	T x, y;

	Point2D(): x(0), y(0) {
	}

	Point2D(T x, T y): x(x), y(y) {
	}

	SquareT squaredDist() const {
		return static_cast<SquareT>(x) * x + static_cast<SquareT>(y) * y;
	}

	auto dist() const -> decltype(sqrt(this->squaredDist())) {
		return sqrt(squaredDist());
	}

	double angle() const {
		return atan2(y, x);
	}

	Point2D& operator-=(const Point2D& rhs) {
		x -= rhs.x;
		y -= rhs.y;
		return *this;
	}

	Point2D& operator+=(const Point2D& rhs) {
		x += rhs.x;
		y += rhs.y;
		return *this;
	}

	Point2D& operator*=(T rhs) {
		x *= rhs;
		y *= rhs;
		return *this;
	}

	Point2D& operator/=(T rhs) {
		x /= rhs;
		y /= rhs;
		return *this;
	}

	T& operator[](size_t i) {
		if (i == 0) {
			return x;
		}
		if (i == 1) {
			return y;
		}
		SPCPPL_ASSERT(false);
	}

	const T& operator[](size_t i) const {
		if (i == 0) {
			return x;
		}
		if (i == 1) {
			return y;
		}
		SPCPPL_ASSERT(false);
	}

	template <typename U, typename V = U>
	Point2D<U, V> as() {
		return {U(x), U(y)};
	}

	Point2D normalized() const {
		static_assert(std::is_floating_point<T>::value, "only implemented for floating point types");
		return *this / dist();
	}

	Point2D rotated(double angle) const {
		static_assert(std::is_floating_point<T>::value, "only implemented for floating point types");
		double co = cos(angle);
		double si = sin(angle);
		return Point2D(x * co - y * si, x * si + y * co);
	}
};

template <typename T, typename S>
Point2D<T, S> operator+(const Point2D<T, S>& lhs, const Point2D<T, S>& rhs) {
	return Point2D<T, S>(lhs.x + rhs.x, lhs.y + rhs.y);
}

template <typename T, typename S>
Point2D<T, S> operator-(const Point2D<T, S>& lhs, const Point2D<T, S>& rhs) {
	return Point2D<T, S>(lhs.x - rhs.x, lhs.y - rhs.y);
}

template <typename T, typename S>
Point2D<T, S> operator*(const Point2D<T, S>& lhs, T rhs) {
	return Point2D<T, S>(lhs.x * rhs, lhs.y * rhs);
}

template <typename T, typename S>
Point2D<T, S> operator*(T lhs, const Point2D<T, S>& rhs) {
	return Point2D<T, S>(lhs * rhs.x, lhs * rhs.y);
}

template <typename T, typename S>
Point2D<T, S> operator/(const Point2D<T, S>& lhs, T rhs) {
	return Point2D<T, S>(lhs.x / rhs, lhs.y / rhs);
}

template <typename T, typename S>
S operator*(const Point2D<T, S>& lhs, const Point2D<T, S>& rhs) {
	return static_cast<S>(lhs.x) * rhs.y - static_cast<S>(rhs.x) * lhs.y;
}

template <typename T, typename S>
S operator%(const Point2D<T, S>& lhs, const Point2D<T, S>& rhs) {
	return static_cast<S>(lhs.x) * rhs.x + static_cast<S>(lhs.y) * rhs.y;
}

template <typename T, typename S>
bool operator==(const Point2D<T, S>& lhs, const Point2D<T, S>& rhs) {
	return lhs.x == rhs.x && lhs.y == rhs.y;
}

template <typename T, typename S>
bool operator!=(const Point2D<T, S>& lhs, const Point2D<T, S>& rhs) {
	return !(lhs == rhs);
}

struct LexicograficallyLess {
	template <typename T, typename S>
	bool operator()(const Point2D<T, S>& lhs, const Point2D<T, S>& rhs) const {
		return std::tie(lhs.x, lhs.y) < std::tie(rhs.x, rhs.y);
	};
};

template <typename T, typename S>
struct LessByAngle {
	explicit LessByAngle(const Point2D<T>& center): center(center) {
	}

	bool operator() (Point2D<T, S> lhs, Point2D<T, S> rhs) {
		lhs -= center;
		rhs -= center;
		if (upper(lhs) != upper(rhs)) {
			return upper(rhs);
		}
		return lhs * rhs > 0;
	}
private:
	bool upper(const Point2D<T>& point) {
		return point.y > 0 || (point.y == 0 && point.x > 0);
	}
	Point2D<T, S> center;
};

template <typename T, typename S>
double distance_to_segment(const Point2D<T, S>& point, const Point2D<T, S>& b, const Point2D<T, S>& c) {
	static_assert(std::is_floating_point<T>::value, "only implemented for floating point types");
	auto ba = b - point;
	auto ca = c - point;
	if ((ba - ca) % ba >= 0 && (ca - ba) % ca >= 0) {
		return fabs(ba * ca) / (ca - ba).dist();
	}
	return std::min(ba.dist(), ca.dist());
};

template <typename T, typename S>
double distance_to_line(const Point2D<T, S>& point, const Point2D<T, S>& b, const Point2D<T, S>& c) {
	static_assert(std::is_floating_point<T>::value, "only implemented for floating point types");
	auto ba = b - point;
	auto ca = c - point;
	return fabs(ba * ca) / (ca - ba).dist();
};

#include <vector>


#include <iterator>


/**
* Support decrementing and multi-passing, but not declared bidirectional(or even forward) because
* it's reference type is not a reference.
*
* It doesn't return reference because
* 1. Anyway it'll not satisfy requirement [forward.iterators]/6
*   If a and b are both dereferenceable, then a == b if and only if *a and
*   b are bound to the same object.
* 2. It'll not work with reverse_iterator that returns operator * of temporary which is temporary for this iterator
*
* Note, reverse_iterator is not guaranteed to work  now too since it works only with bidirectional iterators,
* but it's seems to work at least on my implementation.
*
* It's not really useful anywhere except iterating anyway.
*/
template <typename T>
class IntegerIterator: public std::iterator<std::input_iterator_tag, T, std::ptrdiff_t, T*, T> {
public:
	explicit IntegerIterator(T value): value(value) {

	}

	IntegerIterator& operator++() {
		++value;
		return *this;
	}

	IntegerIterator operator++(int) {
		IntegerIterator copy = *this;
		++value;
		return copy;
	}

	IntegerIterator& operator--() {
		--value;
		return *this;
	}

	IntegerIterator operator--(int) {
		IntegerIterator copy = *this;
		--value;
		return copy;
	}

	T operator*() const {
		return value;
	}

	bool operator==(IntegerIterator rhs) const {
		return value == rhs.value;
	}

	bool operator!=(IntegerIterator rhs) const {
		return !(*this == rhs);
	}

private:
	T value;
};

template <typename T>
class IntegerRange {
public:
	IntegerRange(T begin, T end): begin_(begin), end_(end) {
		SPCPPL_ASSERT(begin <= end);
	}

	IntegerIterator<T> begin() const {
		return IntegerIterator<T>(begin_);
	}

	IntegerIterator<T> end() const {
		return IntegerIterator<T>(end_);
	}

private:
	T begin_;
	T end_;
};

template <typename T>
class ReversedIntegerRange {
	typedef std::reverse_iterator<IntegerIterator<T>> IteratorType;
public:
	ReversedIntegerRange(T begin, T end): begin_(begin), end_(end) {
		SPCPPL_ASSERT(begin >= end);
	}

	IteratorType begin() const {
		return IteratorType(IntegerIterator<T>(begin_));
	}

	IteratorType end() const {
		return IteratorType(IntegerIterator<T>(end_));
	}

private:
	T begin_;
	T end_;
};

template <typename T>
IntegerRange<T> range(T to) {
	return IntegerRange<T>(0, to);
}

template <typename T>
IntegerRange<T> range(T from, T to) {
	return IntegerRange<T>(from, to);
}

template <typename T>
IntegerRange<T> inclusiveRange(T to) {
	return IntegerRange<T>(0, to + 1);
}

template <typename T>
IntegerRange<T> inclusiveRange(T from, T to) {
	return IntegerRange<T>(from, to + 1);
}

template <typename T>
ReversedIntegerRange<T> downrange(T from) {
	return ReversedIntegerRange<T>(from, 0);
}

template <typename T>
ReversedIntegerRange<T> downrange(T from, T to) {
	return ReversedIntegerRange<T>(from, to);
}

template <typename T>
ReversedIntegerRange<T> inclusiveDownrange(T from) {
	return ReversedIntegerRange<T>(from + 1, 0);
}

template <typename T>
ReversedIntegerRange<T> inclusiveDownrange(T from, T to) {
	return ReversedIntegerRange<T>(from + 1, to);
}


using namespace std;

class TaskB {
public:
	void solve(std::istream& in, std::ostream& out) {
		using P = Point2D<double>;
		vector<P> p(3);
		for (int i: range(3)) {
			in >> p[i].x >> p[i].y;
		}

		vector<double> dist(3);
		for (int i: range(3)) {
			dist[i] = (p[i] - p[(i + 1) % 3]).dist();
		}

		vector<double> angles(3);


		auto angle = [&](double c, double b, double a) {
			return acos((-c * c + a * a + b * b)/2/a/b);
		};
		for (int i: range(3)) {
			angles[i] = angle(dist[i], dist[(i + 1) % 3], dist[(i + 2) % 3]);
		}


		double ans = 0;
		for (int i: range(3)) {
			//cerr << dist[i] << ' ' << angles[i % 3] << endl;
			double r = 2 + 1 / tan(angles[(i + 1) % 3] / 2.0) + 1 / tan(angles[(i + 2) % 3] / 2.0);
			r = dist[i] / r;
			ans = max(ans, r);
		}

		out << ans << "\n";

	}
};


int main() {
	std::ios_base::sync_with_stdio(false);
	TaskB solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	in.tie(nullptr);
	out << std::fixed;
	out.precision(20);
	solver.solve(in, out);
	return 0;
}


Measured memory_bytes: 384