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: 1 , 6 , 16 , 31 , 51 , ( . . . . ) 
Options: a ) 61 , b ) 66 , c ) 76 , d ) 86 , e ) 83

Ex Output:
b


Ex Input:
Problem: if x / y = 7 / 3 , then ( x + y ) / ( x - y ) = ? 
Options: a ) 5 , b ) 5 / 2 , c ) - 1 / 6 , d ) - 1 / 5 , e ) - 5

Ex Output:
b


Ex Input:
Problem: find the remainder of the division ( 2 ^ 14 ) / 7 . 
Options: a ) 1 , b ) 2 , c ) 3 , d ) 4 , e ) 5

Ex Output:

d