# frozen_string_literal: true

a, b, x = gets.split.map(&:to_f)

if x > a**2 * b / 2
  puts 90 - Math.atan(a**3 / (2 * a**2 * b - 2 * x)) * 180 / Math::PI
else
  puts 90 - Math.atan(2 * x / (a * b**2)) * 180 / Math::PI
end