using static System.Math;
using System;

public class Hello
{
    static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        var a = int.Parse(line[0]);
        var b = int.Parse(line[1]);
        var c = int.Parse(line[2]);
        getAns(a, b, c);
    }
    static void getAns(int a, int b, int c)
    {
        var s = (a + b + c) / 2;
        var aa = Sqrt((double)s * (s - a) * (s - b) * (s - c));
        Console.WriteLine(aa / s);
    }
}