from collections import defaultdict, Counter

from itertools import product, groupby, count, permutations, combinations

from math import pi, sqrt

from collections import deque

from bisect import bisect, bisect_left, bisect_right

INF = float("inf")

 

 

def main():

    N = int(eval(input()))

    ans = 0

    for i in range(10**9):

        if i * i <= N:

            ans = max(ans, i * i)

        else:

            break

    print(ans)

 

 

if __name__ == '__main__':

    main()
from collections import defaultdict, Counter

from itertools import product, groupby, count, permutations, combinations

from math import pi, sqrt

from collections import deque

from bisect import bisect, bisect_left, bisect_right

from string import ascii_lowercase

from functools import lru_cache

import sys

sys.setrecursionlimit(10000)

INF = float("inf")

YES, Yes, yes, NO, No, no = "YES", "Yes", "yes", "NO", "No", "no"

dy4, dx4 = [0, 1, 0, -1], [1, 0, -1, 0]





def inside(y, x, H, W):

    return 0 <= y < H and 0 <= x < W





def ceil(a, b):

    return (a + b - 1) // b





def main():

    N = int(eval(input()))

    i = 1

    while i * i <= N:

        i += 1

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





if __name__ == '__main__':

    main()

from collections import defaultdict, Counter
from itertools import product, groupby, count, permutations, combinations
from math import pi, sqrt
from collections import deque
from bisect import bisect, bisect_left, bisect_right

INF = float("inf")


def main():
    N = int(eval(input()))
    ans = 0
    for i in range(10**9):
        if i * i <= N:
            ans = max(ans, i * i)
        else:
            break
    print(ans)


if __name__ == "__main__":
    main()

from collections import defaultdict, Counter
from itertools import product, groupby, count, permutations, combinations
from math import pi, sqrt
from collections import deque
from bisect import bisect, bisect_left, bisect_right
from string import ascii_lowercase
from functools import lru_cache
import sys

sys.setrecursionlimit(10000)
INF = float("inf")
YES, Yes, yes, NO, No, no = "YES", "Yes", "yes", "NO", "No", "no"
dy4, dx4 = [0, 1, 0, -1], [1, 0, -1, 0]


def inside(y, x, H, W):
    return 0 <= y < H and 0 <= x < W


def ceil(a, b):
    return (a + b - 1) // b


def main():
    N = int(eval(input()))
    i = 1
    while i * i <= N:
        i += 1
    print(((i - 1) * (i - 1)))


if __name__ == "__main__":
    main()

+from string import ascii_lowercase +from functools import lru_cache +import sys +sys.setrecursionlimit(10000) +YES, Yes, yes, NO, No, no = "YES", "Yes", "yes", "NO", "No", "no" +dy4, dx4 = [0, 1, 0, -1], [1, 0, -1, 0] + + +def inside(y, x, H, W): +    return 0 <= y < H and 0 <= x < W + + +def ceil(a, b): +    return (a + b - 1) // b -    ans = 0 -    for i in range(10**9): -        if i * i <= N: -            ans = max(ans, i * i) -        else: -            break -    print(ans) +    i = 1 +    while i * i <= N: +        i += 1 +    print(((i - 1) * (i - 1)))