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

c = x / (a ** 2)
s = a * c

if s >= a * b / 2
  y = 2 * b - 2 * s / a
  p Math.atan(y/a) * 180 / Math::PI
else
  y = 2 * s / b
  p Math.atan(b/y) * 180 / Math::PI
end