output_description: Print the largest square number not exceeding N.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
attempt: import sys, os, math, bisect, itertools, collections, heapq, queue
  
  # from scipy.sparse.csgraph import csgraph_from_dense, floyd_warshall
  from decimal import Decimal
  from collections import defaultdict, deque
  
  sys.setrecursionlimit(10000000)
  
  ii = lambda: int(sys.stdin.buffer.readline().rstrip())
  il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
  fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
  iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]
  
  iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
  sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
  isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]
  
  lcm = lambda x, y: (x * y) // math.gcd(x, y)
  
  MOD = 10**9 + 7
  MAX = float("inf")
  
  
  def main():
      if os.getenv("LOCAL"):
          sys.stdin = open("input.txt", "r")
  
      N = ii()
  
      ret = 0
      for n in range(int(N**0.5) + 1):
          if n * n <= N:
              ret = max(ret, n * n)
      print(ret)
  
  
  if __name__ == "__main__":
      main()
  
problem_description: 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.
samples: [{"input": "10", "output": "9\n    \n\n10 is not square, but 9 = 3 \u00d7 3 is. Thus, we print 9.\n\n* * *"}, {"input": "81", "output": "81\n    \n\n* * *"}, {"input": "271828182", "output": "271821169"}]