a, b, x = gets.split.map(&:to_f)
if a * a * b >= 2 * x
  h = 2 * x / a / b / b
  puts 90 - Math.atan(h) / Math::PI * 180
else
  h = 2 * (x - a * a * b) / a / a / a
  puts Math.atan(h).abs / Math::PI * 180
end