Using Non-Static classes in using block as directive in C# 6

namespace UsingStatic1
{
    public class Class1
    {
        public static int Add(int x, int y)
        {
            return x + y;
        }
    }
}

using static UsingStatic1.Class1;
namespace UsingStatic
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = Add(20, 30);
        }
    }
}