What is my cost basis for inherited real estate that I sold in 2025. Is it the FMV on date of death? Or the discounted, minority interest from the estate tax return?

Property was appraised at $67,500. My father owned 40%. My sister and I split that. My interest in the $67,500 was then 20% or $13,500. My father's estate tax return claimed a minority interest discount value of $14,650. Is my cost basis 20% of the $67,500? Or is my cost basis 50% of the $14,650?