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: if xy denotes x is raised to the power y , find the last two digits of 19413843 + 19614181 
Options: a ) 67 , b ) 97 , c ) 55 , d ) 32 , e ) 62

Ex Output:
e


Ex Input:
Problem: it takes 30 days to fill a laboratory dish with bacteria . if the size of the bacteria doubles each day , how long did it take for the bacteria to fill one sixteenth of the dish ? 
Options: a ) 16 days , b ) 26 days , c ) 27 days , d ) 28 days , e ) 29 days

Ex Output:
b


Ex Input:
Problem: which number should replace both the asterisks in ( * / 21 ) x ( * / 189 ) = 1 ? 
Options: a ) 21 , b ) 63 , c ) 3969 , d ) 147 , e ) 167

Ex Output:

b