import scala.io.StdIn

object Main extends App {
  val Array(a, b, c) = StdIn.readLine().trim.split(" ").map(_.toInt)

  val (max, s1, s2) = if(a >= b && a >= c) (a, a - b, a - c)
  else if(b >= a && b >= c) (b, b - a, b - c)
  else if(c >= a && c >= b) (c, c - a, c - b)
  else (0, 0, 0)
  
  val (r1, s3) = if(s1 > s2) (s2, s1-s2) else (s1, s2-s1)
  val r2 = s3 / 2
  

  println(r1 + r2)
}