Module _20191029

    Sub Main()
        'https://atcoder.jp/contests/abc144/tasks/abc144_a

        Dim sRead As String = Console.ReadLine()

        Dim iNumber1 As Integer = sRead.Split(" ")(0)
        Dim iNumber2 As Integer = sRead.Split(" ")(1)

        If iNumber1 > 0 AndAlso iNumber1 < 10 AndAlso iNumber2 > 0 AndAlso iNumber2 < 10 Then

            Console.WriteLine(iNumber1 * iNumber2)

        Else

            Console.WriteLine(-1)

        End If

    End Sub

End Module
