input: Write a function to determine if a number has an odd number of divisors. If it does, return True; otherwise, return False. If the number is less than 1, return False.
  assert odd_divisors(-1)==False
  assert odd_divisors(0)==False
  assert odd_divisors(1)==True
  assert odd_divisors(4)==True
  assert odd_divisors(10)==False
output: def odd_divisors(n):
      if n < 1:
          return False
      count = 0
      for i in range(1, n + 1):
          if n % i == 0:
              count += 1
      return count % 2 != 0