import java.util.*;
fun main(args: Array<String>) {
    val sc = Scanner(System.`in`)
    val n = Scanner(System.`in`)
    println(ans(n))
}
 
fun ans(n:Int):Int{
    if(sc in 1..9){
        if(n in 1..9){
          return sc * n
            
        }
    }
    return -1
}