#define floor(x) ((x*2.0-0.5) Shr 1)

Function isPrime(Byval p As Integer) As Boolean
    If p < 2 Then Return False
    If p Mod 2 = 0 Then Return p = 2
    If p Mod 3 = 0 Then Return p = 3
    Dim As Integer d = 5
    While d * d <= p
        If p Mod d = 0 Then Return False Else d += 2
        If p Mod d = 0 Then Return False Else d += 4
    Wend
    Return True
End Function

Function isCircularPrime(Byval p As Integer) As Boolean
    Dim As Integer n = floor(Log(p)/Log(10))
    Dim As Integer m = 10^n, q = p
    For i As Integer = 0 To n
        If (q < p Or Not isPrime(q)) Then Return false
        q = (q Mod m) * 10 + floor(q / m)
    Next i
    Return true
End Function

Dim As Integer p = 2, dp = 1, cont = 0
Print("Primeros 19 primos circulares:")
While cont < 19
    If isCircularPrime(p) Then Print p;" "; : cont += 1
    p += dp: dp = 2
Wend
Sleep