import math._
import scala.collection.mutable.ArrayBuffer

object Main {
  def calc(s: String) {
    val xs = new ArrayBuffer[(String, Int)]

    val buf = new ArrayBuffer[Char]
    var len = 0
    for (c <- s) c match {
      case 'ｗ' => len += 1
      case _ => {
        if (len > 0 && !buf.isEmpty) {
          xs.append((buf.mkString, len))
          buf.clear
        }
        len = 0
        buf.append(c)
        // println(buf)
      }
    }

    if (len > 0 && !buf.isEmpty) xs.append((buf.mkString, len))

    if (xs.isEmpty) println()
    else {
      val longest = xs.maxBy(_._2)._2
      for ((s, _) <- xs.filter(_._2 == longest)) {
        println(s)
      }
    }
  }

  def main(args: Array[String]) {
    val sc = new java.util.Scanner(System.in)
    val s = sc.nextLine
    calc(s)
  }
}