using System;
using System.Collections;
using System.Collections.Generic;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		Console.WriteLine(ReplaceAll("/]a", new[] { '/', ']' }, 'a'));
		Console.WriteLine(ReplaceAll("^/]a",new[] { '^', '/', ']' }, '$'));
	}
	public static string ReplaceAll(string str, char[] charsToReplace, char replacementCharacter)
	{
	    if(string.IsNullOrEmpty(str))
	    {
	        return string.Empty;
	    }
	    
	    var pattern = $"[{string.Concat(charsToReplace).Replace(@"\", @"\\").Replace("-", @"\-").Replace("^", @"\^").Replace("]", @"\]")}]";
	    return Regex.Replace(str, pattern, replacementCharacter.ToString());
	}
}