Imports System
Module FindABProgram
' Function to check if a number is prime
Function isPrime(n As Integer) As Boolean
If n <= 1 Then Return False
If n <= 3 Then Return True
If (n Mod 2 = 0) OrElse (n Mod 3 = 0) Then Return False
Dim limit As Integer = CInt(Math.Sqrt(n))
Dim i As Integer = 5
While i <= limit
If (n Mod i = 0) OrElse (n Mod (i + 2) = 0) Then
Return False
End If
i += 6
End While
Return True
End Function
' Function to find the two prime factors A and B
Sub findAB(N As Integer, ByRef A As Integer, ByRef B As Integer)
Dim limit As Integer = CInt(Math.Sqrt(N))
For i As Integer = 2 To limit
If N Mod i = 0 Then
Dim j As Integer = N \ i
If isPrime(i) AndAlso isPrime(j) Then
A = i
B = j
Exit Sub
End If
End If
Next
A = -1
B = -1 ' No prime factors found
End Sub
Sub Main()
Dim N As Integer = 12349
Dim A As Integer
Dim B As Integer
findAB(N, A, B)
If A <> -1 Then
Console.WriteLine("A = " & A & ", B = " & B)
Else
Console.WriteLine("Not found.")
End If
End Sub
End Module
' run:
'
' A = 53, B = 233
'
