I have a text field on my form actually its like GMT time. I want the users to 
enter integers like '+5' '+6' or '-6' or '-5' etc.

I want to make it easy for users so that they don't have to write '**+**' or '**-**' by there self. There should be by default option of '**+**' or '**-**' as first character in text field.

*I saw some solutions like making a simple drop down in front and user can select from there which will automatically appear in text box.* 

But i want to make it more easy if some other easy solution is there.

will prefer using HTML5 but if not than jquery will be fine..