Problem Statement

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

Input

Input is given from Standard Input in the following format:
N

Output

Print the answer as an integer.

Constraints

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

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.

见题面 Input 部分

见题面 Output 部分