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

Ex Input:
Problem: the sum of the even numbers between 1 and n is 89 * 90 , where n is an odd number , then n = ?

Ex Output:
179


Ex Input:
Problem: zachary is helping his younger brother , sterling , learn his multiplication tables . for every question that sterling answers correctly , zachary gives him 3 pieces of candy . for every question that sterling answers incorrectly , zachary takes away two pieces of candy . after 6 questions , if sterling had answered 2 more questions correctly , he would have earned 31 pieces of candy . how many of the 6 questions did zachary answer correctly ?

Ex Output:
7


Ex Input:
Problem: find the area of the quadrilateral of one of its diagonals is 28 cm and its off sets 9 cm and 6 cm ?

Ex Output:

210 cm 2