using System;

using System.Text.RegularExpressions;                   

public class Program

{

    public static void Main()

    {

        string input = "For example: TM000013452S20548, PB000013452S3DVSF.";

        var matches = Regex.Matches(input, @"(?:TM|PB)0{0,}(\d+)");

        foreach(Match m in matches)

            Console.WriteLine(int.Parse(m.Groups[1].Value));  

    }

}