alias :math, as: Math
defmodule Main do
  def main do
    [a, b, x] =
      IO.read(:line)
      |> String.trim
      |> String.split(" ")
    a = String.to_integer(a)
    b = String.to_integer(b)
    x = String.to_integer(x)
    y = x / a;
    if y > a * b / 2 do
    	IO.puts(Math.atan2((a*b-y)*2, a*a) * 180 / Math.pi())
    else
    	IO.puts(Math.atan2(b*b, y*2) * 180 / Math.pi())
    end
  end
end
