Problem:
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

Solution in Python (3.4.3) (judge verdict: Accepted)

#インポート
import sys

#入力用
def ILI(): return list(map(int, sys.stdin.readline().rstrip().split()))
def ISI(): return map(int, sys.stdin.readline().rstrip().split())
def II(): return int(sys.stdin.readline().rstrip())
def ISS(): return sys.stdin.readline().rstrip().split()
def IS(): return sys.stdin.readline().rstrip()

N = II()
i = 1
while i**2 <= N:
    i += 1
print((i-1)**2)