Problem Statement

For an integer $x$, let $f(x)$ be the number of leading ones in the decimal notation of $x$. For example, we have $f(1)=1,f(2)=0,f(10)=1,f(11)=2,f(101)=1$.

Given an integer $N$, find $f(1)+f(2)+\cdots+f(N)$.

Constraints

• $1 \leq N \leq 10^{15}$
• All values in input are integers.

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer.