40 points for the No.1 choice
30 points for No.2 choice
20 points for No.3 choice
10 points for No.4 choice if at all anyone ranks upto 4

Add all the points gained by each candidates(Prof).
Will be ranked acording to the points gained.
Anybody with points lower than 1/8 th of the higest score will not be ranked.
Eg. X earned 800 points totally
y earned 250 points
z earned 90 points

then:
X - 1st
y - 2nd
(z will not be ranked) -just a simple ranking system.