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

r = 45.to_f
if x <= a * a * b / 2
  r = (Math.atan(x.to_f / (b**2 * a) * 2) - Math::PI / 2) * 180 / Math::PI * -1
else
  r = Math.atan(((a.to_f * a * b) - x) /(a**3) * 2) * 180 / Math::PI
end

puts r

