str = @"abc ""def"" ghi """"jkl"""" mn";

namespace ConsoleQuotes
{
    class Program
    {
        static void Main(string[] args)
        {
            string str = @"abc ""def"" ghi """"jkl"""" mn";
            Console.WriteLine(str);
            //abc "def" ghi ""jkl"" mn
        }
    }
}