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: gold is 19 times as heavy as water and copper is 9 times as heavy as water . in what ratio should these be mixed to get an alloy 15 times as heavy as water ? 
Options: a ) 3 : 2 , b ) 3 : 8 , c ) 5 : 7 , d ) 3 : 7 , e ) 3 : 6

Ex Output:
a


Ex Input:
Problem: a number x is multiplied with itself and then added to the product of 4 and x . if the result of these two operations is - 3 , what is the value of x ? 
Options: a ) - 4 , b ) - 1 and - 3 , c ) 2 , d ) 4 , e ) can not be determined .

Ex Output:

b