import math

n = int(eval(input()))



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

    ans= math.sqrt(i)

    sq= int(ans)

    sq=float(sq)

    #print(ans,sq)

    if sq==ans:

        print(i)

        break



import sys

def fastio():

    from io import StringIO

    from atexit import register

    global input

    sys.stdin = StringIO(sys.stdin.read())

    input = lambda : sys.stdin.readline().rstrip('\r\n')

    sys.stdout = StringIO()

    register(lambda : sys.__stdout__.write(sys.stdout.getvalue()))

fastio()



INF = 10**20

MOD = 10**9 + 7

I = lambda:list(map(int,input().split()))

# from math import gcd

from math import ceil

from collections import defaultdict as dd, Counter

from bisect import bisect_left as bl, bisect_right as br



n, = I()

print((int(n ** 0.5) ** 2))
import math

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

import sys


def fastio():
    from io import StringIO
    from atexit import register

    global input
    sys.stdin = StringIO(sys.stdin.read())
    input = lambda: sys.stdin.readline().rstrip("\r\n")
    sys.stdout = StringIO()
    register(lambda: sys.__stdout__.write(sys.stdout.getvalue()))


fastio()
INF = 10**20
MOD = 10**9 + 7
I = lambda: list(map(int, input().split()))
# from math import gcd
from math import ceil
from collections import defaultdict as dd, Counter
from bisect import bisect_left as bl, bisect_right as br

(n,) = I()
print((int(n**0.5) ** 2))

-import math +import sys -n = int(eval(input())) -for i in range(n, 0, -1): -    ans = math.sqrt(i) -    sq = int(ans) -    sq = float(sq) -    # print(ans,sq) -    if sq == ans: -        print(i) -        break + +def fastio(): +    from io import StringIO +    from atexit import register + +    global input +    sys.stdin = StringIO(sys.stdin.read()) +    input = lambda: sys.stdin.readline().rstrip("\r\n") +    sys.stdout = StringIO() +    register(lambda: sys.__stdout__.write(sys.stdout.getvalue())) + + +fastio() +INF = 10**20 +MOD = 10**9 + 7 +I = lambda: list(map(int, input().split())) +# from math import gcd +from math import ceil +from collections import defaultdict as dd, Counter +from bisect import bisect_left as bl, bisect_right as br + +(n,) = I() +print((int(n**0.5) ** 2))