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

Ex Input:
Problem: if a - b = 5 and a 2 + b 2 = 31 , find the value of ab .

Ex Output:
3


Ex Input:
Problem: a company pays 12.5 % dividend to its investors . if an investor buys rs . 60 shares and gets 25 % on investment , at what price did the investor buy the shares ?

Ex Output:
30


Ex Input:
Problem: if p represents the product of the first 16 positive integers , then p is not a multiple of

Ex Output:

5