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

if x >= (a * b)/2
  s = a * b - x
  l = 2 * s / a
  r = Math.atan(l / a) * 180 / Math::PI
else
  l = 2 * x / b
  r = Math.atan(b / l) * 180 / Math::PI
end

puts r
