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

def solve(a, b, x)
  if 0.5 * a**2 * b < x then
    return Math.atan((2.0 * a**2 * b - 2.0 * x) / a ** 3)
  else
    return 0.5 * Math::PI - Math.atan(2.0 * x / (1.0 * a * b**2))
  end
end

puts solve(a, b, x) * 180.0 / Math::PI
