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CSharp · Console

/Program.cs

using System;
using System.Text.RegularExpressions;
using System.Linq;

public class Program
{
	public static void Main()
	{
		var input = "  P.O, Box123;";
		var pattern = @"^ *|\.|,|;";
		var result = Regex.Replace(input, pattern, "");
		Console.WriteLine(result);
	}
}