How do I write the following formula?

If cell A is greater than Cell B, Cell `C = C-A`; If cell B is greater than Cell A, cell `C = C-B`

I tried to write it like this: 

```
=IF(OR(C3>A3,C3-A3),IF(C3>B3,C3-B3))

```

I have windows 10 and my browser is IE.