Nothing.
That code compiles and runs fine: it produces an output - the word "hello" - and exits. Certainly according to my "internal" compiler it should, and an
Online C Compiler[
^] agrees with me.
If that is what you wanted it to do, then it does it very well.
If it isn't what you wanted it to do, you are going to have to think harder about the task you are trying to perform and code for that!
What makes you think it is wrong?