What do you expect when returning an int? C does not support tuples.
You are using the comma-operator. (ll, kk) is a single expression with the inner expressions (seperated by , - thus the name) being evaluated left to right. All but the rightmost (you can have more than two sub-expressions) results are discarded and the rightmost result is the result of the whole expression. Actually the parenthesis are unnecessary and do not change anything.
