input: Write a python function to find the largest palindrome less than or equal to a given number.
  assert find_largest_palindrome(4400) == 4331
  assert find_largest_palindrome(5000) == 4994
  assert find_largest_palindrome(1000) == 999
output: def find_largest_palindrome(n):
      def is_palindrome(x):
          return str(x) == str(x)[::-1]
      
      for i in range(n, 0, -1):
          if is_palindrome(i):
              return i