'''
Created on 2020/08/28

@author: harurun
'''
def main():
  import math
  import sys
  pin=sys.stdin.readline
  pout=sys.stdout.write
  perr=sys.stderr.write

  N=int(pin())
  for i in range(1,(N+1)//2):
    if N%i==0:
      if (N//i+i)%2==0 and (N//i-i)%2==0:
        print(1)
        return 
  print(-1)
  return 

main()