"""
Problem:
A palindromic number reads the same both ways. The largest palindrome made from
the product of two 2-digit numbers is 9009 = 91 x 99.
Find the largest palindrome made from the product of two 3-digit numbers which
is less than N.
"""
def solution(n):
"""Returns the largest palindrome made from the product of two 3-digit
numbers which is less than n.
>>> solution(20000)
19591
>>> solution(30000)
29992
>>> solution(40000)
39893
"""
answer = 0
for i in range(999, 99, -1): # 3 digit nimbers range from 999 down to 100
for j in range(999, 99, -1):
t = str(i * j)
if t == t[::-1] and i * j < n:
answer = max(answer, i * j)
return answer
if __name__ == "__main__":
print(solution(int(input().strip())))