Comparing Cells + Only displaying unique values.

I'm not sure how to approach this:


Example 1

So, I have 4 cells containing names. Imagine cells A1 to D1 containing:

John | John | Smith | John

Now, I want cell E1 to compare the cells and neatly display each unique name. So I'd want the value of cell E1 to be:

John / Smith


Example 2

John | John | John | John

This should result in just "John" in E1


Example 3

John | Smith | John | Tomato

This should result in "John / Smith / Tomato" in E1

Also, I'd like the names to be in order, so in this third example the result I've shown is what would be expected.

This isn't too complex, in terms of human logic, but I added some examples just in case it wasn't clear enough to build a function.


So yeah, awaiting replies, hopefully someone has an efficient solution to this.