package Yukicoder

/**
 * Created by hichikawa on 2015/11/02.
 */
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 readLineStringArray() : List<String> {
        val str = readLine() as String
        val arrStr = str.split(" ")
        return arrStr
    }
    val arrStr = readLineStringArray()
    val numStr1 = arrStr[0]
    val numStr2 = arrStr[1]
    if (numStr1.length != numStr2.length) {
        if (numStr1.length > numStr2.length) {
            println(numStr1)
            return
        } else {
            println(numStr2)
            return
        }
    } else {
        for (i in 0..(numStr1.length-1)) {
            if (!numStr1[i].equals(numStr2[i])) {
                val n1 = numStr1[i].toString().toInt()
                val n2 = numStr2[i].toString().toInt()
                if (n1 == 7 && n2 == 4) {
                    println(numStr2)
                } else if (n1 == 4 && n2 == 7) {
                    println(numStr1)
                } else if (n1 > n2) {
                    println(numStr1)
                } else {
                    println(numStr2)
                }
                return
            }
        }
        println(numStr1)
    }
}