It says 0N on one side and 4 on the other, it is white and an oval. I live in the u.s
This may be your pill.
Pill imprint NO 4 has been identified as Ondansetron Hydrochloride 4 mg, a generic version of Zofran used for nausea/vomiting.
NO and ON look the same depending which way up you look at it.
You can confirm by checking the image at https://www.drugs.com/imprints/no-4-12870.html
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