how can read data from splited column gridview

See more:

ASP.NET4

Hi friends.
I have created the gridview with splited column. my design is like below.(sorry i cannot able to attach image of gridview)

RollNumber       Name          Subject1            subject2          subject3
                            In        Ex          In       Ex      In        Ex
  
lable           lable       textbox  texbox      textox textbox    textbox textbox

How can read the gridview data. if there is a single column name means it is easy to read the data from the gridview. but here how can read the value of the gridview.