using System;
class Program
{
    static void Main(string[] args)
    {
        var h = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
        double a = h[0];
        double b = h[1];
        double x = h[2];
        double tan;
        if (a*b/2 < x) { tan = -2 * (x / (a * a) - b) / a; }
        else if(a*b/2 == x){tan = b/a;}
        else { tan =  a * b * b / (2*x); }
            
        Console.WriteLine(Math.Atan(tan)*180/Math.PI);
    }
}

