using System;
using System.Text.RegularExpressions;
using System.Collections.Generic;
public class Test
{
	public static void Main()
	{
 
		Regex r = new Regex("^instance[1-9]{1}\\d?$");
 
        List<string> mylist = new List<string>(new string[] { 
        	"instance23", 
        	"instance03", 
        	"instance30", 
        	"instance00", 
        	"instance1", 
        	"instance0", 
        	"instanc101", 
        	"instanc23" 
        	});
 
    	foreach (string s in mylist)
    	{
    		Console.WriteLine(s + ": " + r.IsMatch(s).ToString());		
    	}
 
	}
}

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