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

Ex Input:
Problem: of 30 applicants for a job , 9 had at least 4 years ' experience , 18 had degrees , and 3 had less than 4 years ' experience and did not have a degree . how many of the applicants had at least 4 years ' experience and a degree ?

Ex Output:
10


Ex Input:
Problem: find the area of a parallelogram with base 10 cm and height 20 cm .

Ex Output:
200


Ex Input:
Problem: if p and q are positive integers each greater than 1 , and 17 ( p + 1 ) = 21 ( q + 1 ) , what is the least possible value of p + q ?

Ex Output:

36