using System;
using System.Text.RegularExpressions;

class Demo {
    public static void Main()
    {
        string str = "{ name: \"Phai dấu cuộc tình\", mp3: \"audio\\16\\Phai dau cuoc tinh.mp3\"},{ name: \"Caravan of life\", mp3: \"audio\\4\\Caravan of life.mp3\"},{ name: \"I'm Forbidden\", mp3: \"audio\\11\\I'm Forbidden.mp3\"},{ name: \"Cause i love you\", mp3: \"audio\\6\\Cause i love you.mp3\"},{ name: \"Chỉ là giấc mơ\", mp3: \"audio\\8\\Chi la giac mo.mp3\"},{ name: \"Lột xác\", mp3: \"audio\\12\\Lot xac.mp3\"}";

        foreach (var match in Regex.Matches(str, @"(?<=\\)(\d+)(?=\\)"))
            Console.WriteLine(match);
    }
}