# [BQN](https://mlochbaum.github.io/BQN/), <s>30</s> 28 bytes<sup>[SBCS](https://github.com/mlochbaum/BQN/blob/master/commentary/sbcs.bqn)</sup>
```none
{∾•Fmt¨×⊸/+˝(⥊𝕩-⌜"aA")=⌜↕26}
```

[Run online!](https://mlochbaum.github.io/BQN/try.html#code=RiDihpAge+KIvuKAokZtdMKow5fiirgvK8udKOKlivCdlakt4oycImFBIik94oyc4oaVMjZ9Cgo+4ouI4p+cRsKoIOKfqCJhY2Z6ekEiCiJIZWxsbyBXb3JsZCEiCiItLS0hJiojJCIKIi0tLSEmKiMkYSIKImFhYWFhYWFhYWFhYWFhYWFhYWFhYWFhYWFhYWQi4p+p)

`↕26` Range from 0 to 25.  
`⥊𝕩-⌜"aA"` Differences between each of the characters in the input and a or A.  
`=⌜` Equality table between those two vectors.  
`+˝` Sum the columns.  
`×⊸/` Keep the values with sign 1 (or: remove the zeros)  
`∾•Fmt¨` Convert each value to a string and join.

A slightly different approach using *Bins Down* at 29 bytes:

```none
{∾•Fmt¨×⊸/»1↓/⁼27↕⊸⍋⥊𝕩-⌜"aA"}
```

[Run online!](https://mlochbaum.github.io/BQN/try.html#code=RiDihpAge+KIvuKAokZtdMKow5fiirgvwrsx4oaTL+KBvDI34oaV4oq44o2L4qWK8J2VqS3ijJwiYUEifQoKPuKLiOKfnEbCqCDin6giYWNmenpBIgoiSGVsbG8gV29ybGQhIgoiLS0tISYqIyQiCiItLS0hJiojJGEiCiJhYWFhYWFhYWFhYWFhYWFhYWFhYWFhYWFhYWFkIuKfqQ==)