using System;

using System.Text;

using System.Text.RegularExpressions;

using System.Linq;

using System.Reflection;

using System.Collections;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        int count = 0;

        var b = Regex.Replace("gooodbaaad", "[oa]", m=> { count++; return "x"; });

        Console.WriteLine(b);

        Console.WriteLine(count);

    }

}