The task is to generate the correct answer for a given math problem.

Ex Input:
Problem: which number can we add to 425897 to get a number exactly divisible by 456 ?

Ex Output:
7


Ex Input:
Problem: how many liters of a 40 % iodine solution need to be mixed with 35 liters of a 20 % iodine solution to create a 34 % iodine solution ?

Ex Output:
13


Ex Input:
Problem: find a two digit number , given that the sum of the digits is 9 and the difference of the digits is 3 . ?

Ex Output:

63