import java.util.regex.Matcher
import java.util.regex.Pattern

fun main(args: Array<String>) {
    fun readLineLongArray(): List<Long> {
        val str = readLine() as String
        val arrStr = str.split(" ")
        val ret = arrStr.map { it.toLong() }
        return ret
    }

    fun readLineLong(): Long {
        val str = readLine() as String
        return str.toLong()
    }

    fun readLineInt(): Int {
        val str = readLine() as String
        return str.toInt()
    }

    fun readLineIntArray() : List<Int> {
        val str = readLine() as String
        val arrStr = str.split(" ")
        val ret = arrStr.map { it.toInt() }
        return ret
    }

    fun readLineDoubleArray(): List<Double> {
        val str = readLine() as String
        val arrStr = str.split(" ")
        val ret = arrStr.map { it.toDouble() }
        return ret
    }

    fun readLineDouble() : Double {
        val str = readLine() as String
        return str.toDouble()
    }

    fun readLineString() : String {
        return readLine() as String
    }

    //    fun readLineStringArray(): List<String> {
    //        val str = readLine() as String
    //        val arrStr = str.split(" ")
    //        return arrStr
    //    }

    val str = readLineString()
    var index = 0
    var count = 0
    var maxN = 0
    val p : Pattern = Pattern.compile("ｗ+")
    val m : Matcher = p.matcher(str)
    var list = arrayListOf<String>()
    var lenList = arrayListOf<Int>()
    while (m.find()) {
//        println(m.group())
        count = m.group().length
        if (maxN <= count) {
            list.add(str.substring(index,m.start()))
            lenList.add(count)
            maxN = count
        }
        index = m.end()
    }
    for ((i,item) in lenList.withIndex()) {
        if (item == maxN) {
            println(list[i])
        }
    }
}