Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:

Convert text to sql: What are the names of everybody who has exactly one friend? | person : name , age , city , gender , job | personfriend : name , friend , year | personfriend.friend = person.name | personfriend.name = person.name | 

### Response:

select _ from _ group by _ having count ( _ ) = _ | select name from personfriend group by name having count ( * ) = 1