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

Ex Input:
Problem: joan took out a mortgage from hel local bank . each monthly mortgage payment she makes must be triple the amount of the previous month ' s payment . if her first payment is $ 100 , and the total amount she must pay back is $ 914800 , how many months will it take joan to pay back her mortgage ?

Ex Output:
9


Ex Input:
Problem: a train passes a station platform in 36 sec and a man standing on the platform in 25 sec . if the speed of the train is 54 km / hr . what is the length of the platform ?

Ex Output:
165 


Ex Input:
Problem: the bankers discount of a certain sum of money is rs . 288 and the true discount on the same sum for the same time is rs . 240 . the sum due is :

Ex Output:

1440