Very Big Perfect Squares

Source: UVa

Version: Phuoc Hung OJ Extended

Problem Statement

An integer is a perfect square if it has the form $m^2$ for some integer $m$.

Given a very large natural number $A$, the number of perfect squares from $1$ through $A$ is $\lfloor\sqrt A\rfloor$.

You do not have to print this value exactly. Keep only its most significant digit and replace every following digit by 0. For example, if the exact count is $59$, print 50; if it is $12345$, print 10000.

Input

One line contains the decimal representation of the natural number $A$.

Output

Print the number of perfect squares from $1$ through $A$ in the requested approximate form: keep the first digit and replace all remaining digits by 0.

Subtasks

• Subtask 1 (20%): $1\le A\le10^{18}$.
• Subtask 2 (30%): $A$ has at most $100$ decimal digits.
• Subtask 3 (50%): Full constraints: $1\le A\le10^{1000}$.

Examples

Input

1000

Output

30

Explanation

The exact number of perfect squares not exceeding $1000$ is

The required format keeps the first digit of 31, namely 3, and replaces the remaining digit by 0. Therefore the program prints 30.