Tds on sale of property by nri

i am buying a flat from an NRI which is more than 50lacs. Do i need to deduct TDS of 1% only or also the TDS of 20% on entire sale consideration amount under section u/s 195 of income tax code.

For example an NRI is selling a flat for 80lakhs, then does a buyer have to deduct TDS at 20% on 80lacs(ie16lacs). If suppose by selling the flat,NRI is making a long term capital gain of 5lacs. Then in htis case NRI will be at loss if i deduct TDS at 20%.

Please clarify if my understanding is wrong.