CF305B Continued Fractions

A continued fraction of height $ n $ is a fraction of form . You are given two rational numbers, one is represented as  and the other one is represented as a finite fraction of height $ n $ . Check if they are equal.

The first line contains two space-separated integers $ p,q $ $ (1

Print "YES" if these fractions are equal and "NO" otherwise.

In the first sample . In the second sample . In the third sample .