Background

The more determined a mage is, the luckier they are. — Hall Mage S.

Problem Description

The magic number of the junior mage Xiao M is $2$.

Given a positive integer $n$, Xiao M needs to find the largest even integer $m$ such that $2^m < n$.

Please help him.

Input Format

One line containing one positive integer $n$.

Output Format

One line containing one even integer $m$, which is the answer.

7

2

8

2

1024

8

Hint

Constraints

For the first $20\%$ of the testdata, $n = 2$.

For the first $60\%$ of the testdata, $n$ is a power of $2$.

For $100\%$ of the testdata, $2 \le n \le 10^9$.

Translated by ChatGPT 5