input = gets.chomp.split.map(&:to_f)

a, b, x = input
 
s = x / a
if (a * b / 2) <= s
  h = 2 * (a * b - s) / a
  re = Math.atan2(h, a)
else
  m = 2 * s / b
  re = Math.atan2(b, m)
end
de = re / (2 * Math::PI) * 360
puts de