Given 2 strictly positive integers (therefore `0` isn't a valid input for both inputs), output the difference so that in the first number, the specified index of the second integer will be swapped with the next index. 

## Indexes
Indexes are 1-based, and they wrap around, therefore `4321` given an index of `4` will return `1`, and the next index of that is `4`. So if you are to swap these digits, you get `1324`.

E.g. `1234` -> `2`. We swap the digits `2` and `3`, obtaining `1324`, and then output their difference. We get
`90`.

|Input|Output|
|:---:|:----:|
|`1234`,`2`|`90`|
|`4321`,`4`|`-2997`|