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: how many paying stones , each measuring 2 1 / 2 m * 2 m are required to pave a rectangular court yard 20 m long and 16 1 / 2 m board ? 
Options: a ) 66 , b ) 18 , c ) 16 , d ) 10 , e ) 15

Ex Output:
a


Ex Input:
Problem: what is the least whole number that should be added to 784839 if it is to be divisible by 10 ? 
Options: a ) 3 , b ) 2 , c ) 1 , d ) 5 , e ) 6

Ex Output:
c


Ex Input:
Problem: a high school has 400 students 1 / 2 attend the arithmetic club , 5 / 8 attend the biology club and 3 / 4 attend the chemistry club . 3 / 8 attend all 3 clubs . if every student attends at least one club how many students attend exactly 2 clubs . 
Options: a ) 35 , b ) 45 , c ) 55 , d ) 60 , e ) 50

Ex Output:

e