Hello Mamatha,
I could give it to you directly, but I think it always better to learn how to do it.
Just check out this website where you can create, check and learn regex:
It is really simple and so you can profit it from it in the future!
Hope this helps,
Good luck!
Hi Mamatha,
Use this regular expression : ^[A-Za-z0-9]{3,}$
Hope this helps you,
Thankyou.