a, b, x = gets.chomp.split.map(&:to_f)
v = a * a * b
if x * 2 > v
  res = Math::atan((b / a - x / (a ** 3)) * 2.0)
else
  res = Math::atan(a * b * b / (2.0 * x))
end
puts "%.7f" % [res / Math::PI * 180]