Most of the times and interviewer would intentionally omit some specifics about the problem the candidate must resolve, thus leaving room for questions. The questions the candidate asks in order to complete a certain task are as important as the task itself.
Regarding the above problem, in my opinion it has everything you need for a good understanding. The only thing it's missing would be some limits for n.
If you have trouble understanding this task, it means you have trouble understanding basic algorithmic problems as most of them are defined in a similar manner.
To also, answer jlangenauer's question: this would be a perfect interview task for a junior. If you find many candidates that fail this kind of problems, you should seriously consider a way of better screening your candidates. (phone interview, online tasks, etc).
Regarding the above problem, in my opinion it has everything you need for a good understanding. The only thing it's missing would be some limits for n.
If you have trouble understanding this task, it means you have trouble understanding basic algorithmic problems as most of them are defined in a similar manner.
To also, answer jlangenauer's question: this would be a perfect interview task for a junior. If you find many candidates that fail this kind of problems, you should seriously consider a way of better screening your candidates. (phone interview, online tasks, etc).