Days for the Stick to Shrink to Length 1

Problem Description

Zhuangzi wrote, "A stick one chi long, cut in half each day, will never be exhausted." On the first day there is a stick of length $a$. Starting from the second day, every day the stick is sawn in half (each time divided by $2$, rounded down). On which day will the stick's length become $1$?

(Terminology: rounding down means discarding the fractional part of a division result and keeping only the integer part.)

Input Format

One positive integer $a$, the length of the stick.

Output Format

One positive integer: the day on which the stick's length becomes $1$.

Sample Input

100

Sample Output

7

Constraints

It is guaranteed that $1 \le a \le 10^9$.