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Score : $200$ points

### 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