# ABC077-B

import math

def check(N):

    n = math.sqrt(N)

    return math.floor(n) == math.ceil(n)

N = int(eval(input()))

flag = False

for i in range(N, 0, -1):

    flag = check(i)

    if flag:

        print(i)

        break

        
# ABC077-B 模範解答

N = int(eval(input()))

for i in range(1, N+2):

    if i ** 2 > N:

        print(((i - 1) ** 2))

        break
# ABC077-B
import math


def check(N):
    n = math.sqrt(N)
    return math.floor(n) == math.ceil(n)


N = int(eval(input()))
flag = False
for i in range(N, 0, -1):
    flag = check(i)
    if flag:
        print(i)
        break

# ABC077-B 模範解答
N = int(eval(input()))
for i in range(1, N + 2):
    if i**2 > N:
        print(((i - 1) ** 2))
        break

-# ABC077-B -import math - - -def check(N): -    n = math.sqrt(N) -    return math.floor(n) == math.ceil(n) - - +# ABC077-B 模範解答 -flag = False -for i in range(N, 0, -1): -    flag = check(i) -    if flag: -        print(i) +for i in range(1, N + 2): +    if i**2 > N: +        print(((i - 1) ** 2))