I am trying to select distinct users that are listed for other companies but not on my company (1). Here is an example

```
Placement User Company
1          1      1
2          1      2
3          2      2
4          3      1
5          2      1

```

From this table, I would like to get row 4 since he is in other company (not 1) but listed on others. I do not want others because they are listed on both my company and others. Anyone can help?