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

z = (a**2)*b # 容器の体積

if z / 2.0 <= x # x が半分以上
  n = z - x
  t = (2.0 * n)/(a**2)
  p (Math.atan(t/a) * 180 / Math::PI)
  exit
else
  t = (2.0 * x)/(a * b)
  p (Math.atan(a/t) * 180 / Math::PI)
end
