Positive Squares Below N

Source: Phước Hưng OJ

Version: Phuoc Hung OJ Extended

Problem Statement

Count positive integers i satisfying i*i < n. Exclude the square zero and a square equal to n.

Input

A single integer n.

Output

Count of positive perfect squares strictly below n.

Subtasks

• Subtask 1 (20%): 0 ≤ n ≤ 1000.

• Subtask 2 (30%): 0 ≤ n ≤ 10^8.

• Subtask 3 (50%): 0 ≤ n ≤ 10^12.

Examples

Example 1

Input:

10

Output:

3

Explanation: The qualifying positive squares are 1, 4, and 9.

Example 2

Input:

9

Output:

2

Explanation: The square 9 equals n and must be excluded.

Example 3

Input:

1

Output:

0

Explanation: No positive square is less than one.