#!/bin/env python
# coding:utf-8

import sys

Input = []
while True:
    line = sys.stdin.readline()
    if not line:
      break
    Input.extend(line.split())

In = list(str(int(Input[0])+1))
if len(In) % 2 == 1:
    Mi = len(In) / 2
    for i in xrange(1, Mi+1):
        if int(In[Mi+i]) > int(In[Mi-i]):
            #前半部分的加一(考虑中位是9),逆序拼接
            Mi_int = int(''.join(In[:Mi+1])) + 1
            In = list(str(Mi_int))
            In.extend(In[:-1][::-1])
            break
        elif In[Mi+i] < In[Mi-i]:
            #直接对半拼接
            In = In[:Mi+1]
            In.extend(In[:-1][::-1])
            break
else:
    #组成奇数位，方便比较
    In.insert(len(In)/2, '#')
    Mi = len(In) / 2
    for i in xrange(1,Mi+1):
        if In[Mi+i] > In[Mi-i]:
            Mi_int = int(''.join(In[:Mi])) + 1
            In = list(str(Mi_int))
            In.extend(In[::-1])
            break
        else:
            In = In[:Mi]
            In.extend(In[::-1])
            break

print ''.join(In)