Find time duration between tow times with am pm selecton : I have three dropdown lists for selecting start time and another three for selecting end time .I want asp.net program which will give duration between two time and after i entered start time then end time should be greater than start time .first dropdown list contain 1 to 12 hours ans second contains 0 to 59 minutes and third one is for selecting am/pm.[here is image of that][1]


  [1]: http://i.stack.imgur.com/E8niL.jpg

Give me codebehind for this page..