I can't find the code for my coke rewards inside a fridge pack. can somebody tell me where it is?

I opened the entire box up, and I don't see a code anywhere. Is the code on the flap that you rip off when you put the box in the fridge?

I can't find the code for my coke rewards inside a fridge pack. can somebody tell me where it is?
Its on the flap when you open the box. The outside part is gray. If you are not careful openeing the box you might miss it.

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