import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;

public class Main {
    InputStream is;

    int __t__ = 1;
    int __f__ = 0;
    int __FILE_DEBUG_FLAG__ = __f__;
    String __DEBUG_FILE_NAME__ = "src/A2";

    FastScanner in;
    PrintWriter out;

    public void solve() {
        int x1 = in.nextInt(), y1 = in.nextInt();
        int x2 = in.nextInt(), y2 = in.nextInt();
        int x3 = in.nextInt(), y3 = in.nextInt();

        double d12 = dist(x1, y1, x2, y2);
        double d13 = dist(x1, y1, x3, y3);
        double d23 = dist(x2, y2, x3, y3);

        double a = Math.max(d12, Math.max(d13, d23));
        double r = calcRadius(x1, y1, x2, y2, x3, y3);
        System.out.println((a * r) / (2 * r + a));
    }
/*
    private double calc(int x1, int y1, int x2, int y2, int x3, int y3) {
        double lo = 0, hi = 1.0;
        for (int i = 1; i < 9999; i++) {
            double c1 = calc2(x1, y1, x2, y2, x3, y3, (i - 1) / 10000.0);
            double c2 = calc2(x1, y1, x2, y2, x3, y3, i / 10000.0);
            double c3 = calc2(x1, y1, x2, y2, x3, y3, (i + 1) / 10000.0);
            if (c2 > c1 && c2 > c3) {
                System.out.println(i + " " + calc2(x1, y1, x2, y2, x3, y3, i / 10000.0));
            }
        }

        for (int i = 0; i < 100; i++) {
            double mid1 = lo + (hi - lo) / 3.0;
            double mid2 = lo + 2.0 * (hi - lo) / 3.0;
            double r1 = calc2(x1, y1, x2, y2, x3, y3, mid1);
            double r2 = calc2(x1, y1, x2, y2, x3, y3, mid2);
            // System.out.println(mid1 + " " + mid2);
            if (r1 < r2) {
                lo = mid1;
            } else {
                hi = mid2;
            }
        }
        return calc2(x1, y1, x2, y2, x3, y3, lo);
    }

    private double calc2(int x1, int y1, int x2, int y2, int x3, int y3, double rate) {
        double cx = x2 + (x3 - x2) * rate;
        double cy = y2 + (y3 - y2) * rate;
        double r1 = calcRadius(x1, y1, x2, y2, cx, cy);
        double r2 = calcRadius(x1, y1, x3, y3, cx, cy);
        return Math.min(r1, r2);
    }
*/

    private double calcRadius(double x1, double y1, double x2, double y2, double x3, double y3) {
        double d12 = dist(x1, y1, x2, y2);
        double d13 = dist(x1, y1, x3, y3);
        double d23 = dist(x2, y2, x3, y3);

        double s = (d12 + d13 + d23) / 2;
        double area = Math.sqrt(s * (s - d12) * (s - d13) * (s - d23));
        return area / s;
    }

    private double dist(double x1, double y1, double x2, double y2) {
        double dx = x1 - x2;
        double dy = y1 - y2;
        return Math.sqrt(dx * dx + dy * dy);
    }

    /* MOD_CALCULATION */
    static int MOD = 1_000_000_007;
    static long ADD(long a, long b) {
        return (a + b) % MOD;
    }

    static long SUB(long a, long b) {
        return (a - b + MOD) % MOD;
    }

    static long MULT(long a, long b) {
        return ((a % MOD) * (b % MOD)) % MOD;
    }

    static long POW(long a, long x) {
        long res = 1;
        for ( ; x > 0; x >>= 1) {
            if (x % 2 == 1) res = MULT(res, a);
            a = MULT(a, a);
        }

        return res;
    }

    static long DIV(long a, long b) {
        return MULT(a, POW(b, MOD - 2));
    }
    /* end */

    public void run() {
        if (__FILE_DEBUG_FLAG__ == __t__) {
            try {
                is = new FileInputStream(__DEBUG_FILE_NAME__);
            } catch (FileNotFoundException e) {
                // TODO 自動生成された catch ブロック
                e.printStackTrace();
            }
            System.out.println("FILE_INPUT!");
        } else {
            is = System.in;
        }
        in = new FastScanner(is);
        out = new PrintWriter(System.out);

        solve();
    }

    public static void main(final String[] args) {
        new Main().run();
    }

    class FastScanner {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;

        public FastScanner(InputStream stream) {
            this.stream = stream;
            // stream = new FileInputStream(new File("dec.in"));

        }

        int read() {
            if (numChars == -1)
                throw new InputMismatchException();
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        boolean isEndline(int c) {
            return c == '\n' || c == '\r' || c == -1;
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        int[] nextIntArray(int n) {
            int[] array = new int[n];
            for (int i = 0; i < n; i++)
                array[i] = nextInt();

            return array;
        }

        int[][] nextIntMap(int n, int m) {
            int[][] map = new int[n][m];
            for (int i = 0; i < n; i++) {
                map[i] = in.nextIntArray(m);
            }
            return map;
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        long[] nextLongArray(int n) {
            long[] array = new long[n];
            for (int i = 0; i < n; i++)
                array[i] = nextLong();

            return array;
        }

        long[][] nextLongMap(int n, int m) {
            long[][] map = new long[n][m];
            for (int i = 0; i < n; i++) {
                map[i] = in.nextLongArray(m);
            }
            return map;
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        double[] nextDoubleArray(int n) {
            double[] array = new double[n];
            for (int i = 0; i < n; i++)
                array[i] = nextDouble();

            return array;
        }

        double[][] nextDoubleMap(int n, int m) {
            double[][] map = new double[n][m];
            for (int i = 0; i < n; i++) {
                map[i] = in.nextDoubleArray(m);
            }
            return map;
        }

        String next() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        String[] nextStringArray(int n) {
            String[] array = new String[n];
            for (int i = 0; i < n; i++)
                array[i] = next();

            return array;
        }

        String nextLine() {
            int c = read();
            while (isEndline(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isEndline(c));
            return res.toString();
        }
    }
}


Measured memory_bytes: 21332