How to correctly specify the connection port to MS SQL Exrpess 2012?

Question

C++ / C#

The database server is online on the SERVER computer. I'm trying to connect like this

private string server_adress = @"SERVER\SQLEXPRESS,64256";
SqlConnectionStringBuilder scsBuilder = new SqlConnectionStringBuilder();
            scsBuilder.UserID = "log";
            scsBuilder.Password = "1111";
            scsBuilder.DataSource = server_adress;
            scsBuilder.InitialCatalog = "main_data";
            scsBuilder.IntegratedSecurity = false;

            con = new SqlConnection(scsBuilder.ConnectionString);

"User login failed."
Connection succeeds in SQL Management Studio

Answer 1

64256and there is a port.