In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Ex Input:
Problem: what is the greatest integer m for which the number 30 ! / 10 ^ m is an integer ? 
Options: a ) 7 , b ) 8 , c ) 9 , d ) 10 , e ) 11

Ex Output:
a


Ex Input:
Problem: a father said to his son , ` ` i was as old as you are at the present at the time of your birth ' ' . if the father ' s age is 52 years now , the son ' s age 5 years back was : 
Options: a ) a ) 14 , b ) b ) 67 , c ) c ) 56 , d ) d ) 21 , e ) e ) 34

Ex Output:
d


Ex Input:
Problem: when a random experiment is conducted , the probability that event a occurs is 1 / 4 . if the random experiment is conducted 4 independent times , what is the probability that event a occurs exactly twice ? 
Options: a ) 14 / 65 , b ) 27 / 128 , c ) 33 / 140 , d ) 37 / 165 , e ) 41 / 187

Ex Output:

b