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: s ( n ) is a n - digit number formed by attaching the first n perfect squares , in order , into one integer . for example , s ( 1 ) = 1 , s ( 2 ) = 14 , s ( 3 ) = 149 , s ( 4 ) = 14916 , s ( 5 ) = 1491625 , etc . how many digits r are in s ( 99 ) ? 
Options: a ) r = 350 , b ) r = 353 , c ) r = 354 , d ) r = 356 , e ) 357

Ex Output:
b


Ex Input:
Problem: how many 3 - digit positive integers are there , where each digit is positive , and no 3 adjacent digits are same ? 
Options: a ) 1236 , b ) 504 , c ) 4096 , d ) 4608 , e ) 6561

Ex Output:
b


Ex Input:
Problem: how much water must be added to 60 litres of milk at 1 1 ⁄ 2 litres for 20 so as to have a mixture worth 10 2 ⁄ 3 a litre ? 
Options: a ) 10 litres , b ) 12 litres , c ) 15 litres , d ) 18 litres , e ) none of these

Ex Output:

c