#include <iostream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <numeric>
#include <iterator>
#include <functional>
#include <complex>
#include <queue>
#include <stack>
#include <cmath>
#include <cassert>
#include <cstring>
using namespace std;
typedef long long LL;
typedef complex<double> CMP;

class NextPalindromicNumber { public:
	string getNext(string n) 
	{
		string s = mirror(n);
		if( n < s )
			return s;
		return mirror(plus1(s, (s.size()-1)/2));
	}

	string mirror(const string& s)
	{
		return string(s.begin(), s.begin()+s.size()/2) + string(s.rbegin()+s.size()/2, s.rend());
	}

	string plus1(string s, int i)
	{
		while( s[i] == '9' )
		{
			s[i--] = '0';
			if( i < 0 )
				return '1'+s;
		}
		s[i]++;
		return s;
	}
};

// BEGIN CUT HERE
#include <ctime>
double start_time; string timer()
 { ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
 { os << "{ ";
   for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
   os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
void verify_case(const string& Expected, const string& Received) {
 bool ok = (Expected == Received);
 if(ok) cerr << "PASSED" << timer() << endl;  else { cerr << "FAILED" << timer() << endl;
 cerr << "\to: \"" << Expected << '\"' << endl << "\tx: \"" << Received << '\"' << endl; } }
#define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
#define END	 verify_case(_, NextPalindromicNumber().getNext(n));}
int main(){

CASE(0)
	string n = "12345"; 
	string _ = "12421"; 
END
CASE(1)
	string n = "858"; 
	string _ = "868"; 
END
CASE(2)
	string n = "1999"; 
	string _ = "2002"; 
END
CASE(3)
	string n = "1"; 
	string _ = "2"; 
END
CASE(4)
	string n = "9999"; 
	string _ = "10001"; 
END
/*
CASE(5)
	string n = ; 
	string _ = ; 
END
CASE(6)
	string n = ; 
	string _ = ; 
END
*/
}
// END CUT HERE
