def lscan; gets.split.map(&:to_i); end
def bye(msg); puts msg.to_s; exit; end

a, b, x = lscan.map(&:to_f)

rad = (0.0..(Math::PI/2)).bsearch{|rad|
  h = a*Math.tan(rad)
  l = b/Math.tan(rad)
  v = h < b ? a*a*(b - h/2) : a*b*l/ 2
  v < x
}


p rad/Math::PI*180