require 'pp'

a, b, x = gets.chomp!.split(" ").map(&:to_i)

s = a * a
# 傾けてない状態でのcm
y = x / s.to_f

if a * b * a >= 2 * x
  h = 2 * x.to_f / (b * a)
  r = Math.sqrt(b * b + h * h)

  puts 90 - Math.asin(h / r) * 180 / Math::PI
else
  z = 2 * (b - y)
  r = Math.sqrt(z * z + a * a)
  puts 90 - Math.asin(a.to_f / r) * 180 / Math::PI
end
