I have two lists of the same length. Let's say:

```
x = ['123', '456', '789', '123']
y = ['aaa', 'aaa', 'bbb', 'ccc']

```

They are basically combinations (123-aaa, 456-aaa, 789-bbb, 123-ccc).

What I am trying to accomplish is to get the unique values and the count of unique values in list y, **BUT** only after I have removed all the pairs that have the same value in list x. So in this example I would need to delete x[3], and y[3]. And then have the counts in a dictionary:

```
{'aaa' : '2', 'bbb' : '1'}

```

I hope this is clear enough. Been banging my head against the wall for hours...