How to prevent non-numeric input in VB.NET?

I'm working on a program that requires the user to input an integer. How do I prevent the user from entering a non-numeric value? I tried using the IsNumeric() function but I get an error before I can use it. I get the error at the console.read, before I can call the IsNumeric() function. Here is my code:

Dim num As Integer

    Console.Write("enter num:")
    num = Console.ReadLine 

    If IsNumeric(num) = True Then
        Console.WriteLine("valid. num = " & num)
    Else
        Console.WriteLine("invalid")
    End If

Any help is greatly appreciated.

Try this:

Dim num As Integer

Console.Write("enter num:")
Dim input = Console.ReadLine

If Integer.TryParse(input, num) Then
    Console.WriteLine("valid. num = " & num)
Else
    Console.WriteLine("invalid")
End If