a, b, x = gets.split.map(&:to_f)
v = a ** 2 * b
tv = v - x
if tv <= (v / 2)
  h = tv * 2 / a / a
  puts Math.atan2(h, a) * 180 / Math::PI
else
  h = x * 2 / b / a
  puts 90 - Math.atan2(h, b) * 180 / Math::PI
end

