    import java.util.Scanner;
            public class Main{
              public static void main(String[] args){
                Scanner stdIn = new Scanner(System.in);
                int a = stdIn.nextInt();
                int b = stdIn.nextInt();
                int c = a*b;
                if((a<1)||(a>9)||(b<1)||(b>9)){
                  System.out.println("-1");
                }else{
                  System.out.println(c);
                }
              }
            }
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz