Regarding Cost of Acquisition of property

Khizar khan (10 Points)

28 June 2019  
Suppose there is piece of land that inherited by Mr. X to his son Mr. Y then Mr. Y inherited the same land to his son Mr. Z.
Mr. Z constructed a house on it and sold the house in 2016.
Actual date of purchase and price of property is not available.
how can we calculate Cost of Acquisition in this case.