How to replace particular many spaces by single space...?

Regex r = new Rexgex(@\"\\s+\");
inputstring = r.Replace(inputstring, " ");

protected void Page_Load(object sender, EventArgs e)
    {
        Regex regex = new Regex(@"\>\s+\<");
        string str = "<ol>       <li>one </li>         <li>one       two  </li>  <li>three</li></ol>";
//replacing multiple space with single space
str = regex.Replace(str, new MatchEvaluator(Replacingit));

    }
    public string Replacingit(Match match)
    {
        string temp = match.Value;
//loop until remains single space.
        while (temp.Contains("  "))
        {
            temp = temp.Replace("  ", " ");
        }
        return temp;
    }