Problem Statement

Find the largest square number not exceeding $N$. Here, a square number is an integer that can be represented as the square of an integer.

Constraints

• $1 \\leq N \\leq 10^9$
• $N$ is an integer.

Input

Input is given from Standard Input in the following format:

$N$

Output

Print the largest square number not exceeding $N$.

Sample Input 1

10

Sample Output 1

9

$10$ is not square, but $9 = 3 × 3$ is. Thus, we print $9$.

Sample Input 2

81

Sample Output 2

81

Sample Input 3

271828182

Sample Output 3

271821169