#!/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)