Maximum Even Exponent

Initial apprentice mage Little M possesses the magic number \(2\). Given a positive integer \(n\), Little M needs to find the largest even integer \(m\) such that \(2^m < n\).

Your task is to help him.

inputFormat

The input consists of a single positive integer \(n\) (with \(n > 1\)).

outputFormat

Output the largest even integer \(m\) satisfying \(2^m < n\).

sample

2

0