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.

Input

Input is given from Standard Input in the following format:
N

Output

Print the largest square number not exceeding N.

Constraints

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

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

见题面 Input 部分

见题面 Output 部分