# frozen_string_literal: true

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

h = x / (a * a)

theta = Math.atan(2 / a * (b - h))

l = b - a * Math.tan(theta)

if l < 0
  theta = Math.atan(b * b / (2 * a * h))
end
puts theta / Math::PI * 180
