# [Brachylog], 7 bytes

    d~k≠tℕ₁

[Try it online!][TIO-lelek69o]

[Brachylog]: https://github.com/JCumin/Brachylog
[TIO-lelek69o]: https://tio.run/##SypKTM6ozMlPN/pfXa6koGunoFRu/6htw6Ompoe7Omsfbp3wP6Uu@1HngpJHLVMfNTX@/x8dbaijYKSjYByroxBtrKNgoqMQDxQxBHHNdRQsdBQsgTyQiBFIKN4UKA9SA1QabwRRawCUhJihowCUBuoyNACpBas3hKo3j40FAA "Brachylog – Try It Online"

[Seems][1] not to need an explicit label to function properly.


```
 ~k        Append something to
d          the deduplicated input
   ≠       such that all elements are distinct
    t      and the new last element
     ℕ₁    is a positive integer
           which is output.
```

  [1]: https://tio.run/##SypKTM6ozMlPN/r/vy77UeeCkkctUx81Nf7/Hx1vqqMQbwLExkBsBMSGOgoGOgpAEsgBigGlzYFcg9j/UQA