import math

n = int(eval(input()))



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

    if math.sqrt(i).is_integer():

        print(i)

        break

n = int(eval(input()))



for i in reversed(list(range(1, int(n**0.5)+1))):

    if i**2 <= n:

        print((i**2))

        break

import math

n = int(eval(input()))
for i in range(n, 0, -1):
    if math.sqrt(i).is_integer():
        print(i)
        break

n = int(eval(input()))
for i in reversed(list(range(1, int(n**0.5) + 1))):
    if i**2 <= n:
        print((i**2))
        break

-import math - -for i in range(n, 0, -1): -    if math.sqrt(i).is_integer(): -        print(i) +for i in reversed(list(range(1, int(n**0.5) + 1))): +    if i**2 <= n: +        print((i**2))