Do you think I should steal my classmate's paper and turn it in as my own?
Why would you do that to your classmate?
I want him to suffer
You clearly don't like your classmate but stealing from him just so you can cheat is wrong and makes no sense. You shouldn't be mean enough to just want to steal to punish someone. Just ignore him and work on your own paper.
Oh, the paper was 30 lines. I thought it was 10.
The amount you copied doesn't matter here, it's the principle. Your teacher or classmates will take notice and you'll only end up failing that assignment. If you don't care about learning the material, then don't bother putting in the effort to cheat.