fun main(args: Array<String>){
    val sc: List<String> = readLine()!!.split(" ")
    if(sc[0].toInt() < 10){
        if(sc[1].toInt() < 10){
            println(sc[0].toInt() * sc[1].toInt())
        }else{
            println("-12 ")
        }
    }else{
        println("-1")
    }

}
