"Father of Pain"

If I have Urien, and I roll the D3 to give extra pain tokens to wracks or grots, what if I have less units of those than what the number is?
Example, 1 wrack unit, 1 grot unit, I roll a 3 (5 or 6).
Does the extra pain token
1. Disappear
2. Go to either the wrack or grot unit (so one has 3)
3. Go to Urien himself? (or perhaps another haemonculus?)

Im pretty sure this is one of those questions that has no good answer, but if I have missed something that tells that there is an answer, I dont want to exploit this if I get Urien someday

Each unit up to the number rolled on the D3 receives a pain token. Any excess tokens are lost.

EDIT - to make it clearer you generate a pain token for D3 units, not D3 pain tokens.