fun main(args: Array<String>){
  val input = readLine()!!.split(" ")
  val a = input[0].toDouble()
  val b = input[1].toDouble()
  val x = input[2].toDouble()

  val s = x / a

  println(Math.toDegrees(Math.atan(
    if( a * b / 2 < s )
      ((a*b-s)*2/a)/a
    else if( s == a * b / 2 )
      b/a
    else
      b/(s*2/b)
  )))
}
