object TestMain extends App{
  var num = scala.io.StdIn.readLine()
  var a =  num.split(" ")(0).toInt
  var b =  num.split(" ")(1).toInt
  var c = num.split(" ")(2).toInt

  if (a==b){
    println(c)
  }else if (a==c){
    println(b)
  }else{
    println(a)
  }
}