fun main(args: Array<String>){
    val k = readLine()!!.toInt()
    val n = readLine()!!.toInt()
    val primeList = getPrimeList(n).filter { it >= k }
    val convList = primeList.map { getConv(it) }

    var fromIdx = 0
    var maxLength = 0
    var maxFromIdx = 0
    val dic = mutableMapOf<Int,Boolean>()
    for(i in convList.indices) {
        if(dic.containsKey(convList[i])) {
            for(j in fromIdx..i) {
                dic.remove(convList[j])
                if(convList[j] == convList[i]) {
                    fromIdx = j+1
                    break
                }
            }
        }
        dic[convList[i]] = true
        val len = i - fromIdx + 1
        if(len >= maxLength) {
            maxLength = len
            maxFromIdx = fromIdx
        }
    }
    println(primeList[maxFromIdx])
}

fun getConv(inNum: Int):Int {
    if(inNum < 10) {
        return inNum
    }
    val outNum = getConv((inNum/10) + (inNum%10))
    return outNum
}

fun getPrimeList(maxNum:Int):List<Int> {
    val flags = arrayOfNulls<Boolean>(maxNum+1)
    val list = mutableListOf<Int>()
    for (i in 2..maxNum) {
        if(flags[i] != null && flags[i]!!) {
            continue
        }
        val maxIndex = maxNum/i
        for(j in 1..maxIndex) {
            flags[i*j] = true
        }
        list.add(i)
    }
    return list.toList()
}