Problem Statement

Given a positive integer $N$, find the maximum integer $k$ such that $2^k \\le N$.

Constraints

• $N$ is an integer satisfying $1 \\le N \\le 10^{18}$.

Input

Input is given from Standard Input in the following format:

$N$

Output

Print the answer as an integer.

Sample Input 1

6

Sample Output 1

2

• $k=2$ satisfies $2^2=4 \\le 6$.
• For every integer $k$ such that $k \\ge 3$, $2^k > 6$ holds.

Therefore, the answer is $k=2$.

Sample Input 2

1

Sample Output 2

0

Note that $2^0=1$.

Sample Input 3

1000000000000000000

Sample Output 3

59

The input value may not fit into a $32$-bit integer.