Sardar writing exam

Sardar Gurbachan Singh is appearing for his University final examination which consists of Y/N type questions.

He takes his seat in the Examination hall, stares at the question paper for five minutes, and then in a fit of inspiration takes his wallet out, removes a coin and starts tossing the coin and marking the answer sheet - Y for Heads and N for Tails.

Within half an hour he is all done whereas the rest of the class is sweating it out. During the last few minutes, he is seen desperatley throwing the coin, swearing and sweating.

The invigilator,alarmed, approaches him and asks what is going on. "Oye, I finished the exam in half an hour". "But yaar", he says, " I am rechecking my answers."