F

#include <bits/stdc++.h>

using namespace std;

#define fixed(n) fixed << setprecision(n)
#define ceil(n, m) (((n) + (m) - 1) / (m))
#define add_mod(a, b, m) (((a % m) + (b % m)) % m)
#define sub_mod(a, b, m) (((a % m) - (b % m) + m) % m)
#define mul_mod(a, b, m) (((a % m) * (b % m)) % m)
#define all(vec) vec.begin(), vec.end()
#define rall(vec) vec.rbegin(), vec.rend()
#define sz(x) int(x.size())
#define debug(x) cout << #x << ": " << (x) << "\n";
#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define EPS 1e-9
constexpr int INF = 1 << 30, Mod = 1e9 + 7;
constexpr ll LINF = 1LL << 62;
#define PI acos(-1)
template < typename T = int > using Pair = pair < T, T >;
vector < string > RET = {"NO", "YES"};

template < typename T = int > istream& operator >> (istream &in, vector < T > &v) {
    for (auto &x : v) in >> x;
    return in;
}

template < typename T = int > ostream& operator << (ostream &out, const vector < T > &v) {
    for (const T &x : v) out << x << ' ';
    return out;
}

bool is_all_nine(vector < int >& num, int n){
    for(int i = 0; i < sz(num); ++i)
        if (num[i] != 9)
            return false;
    return true;
}

void get_next_palindrome (vector < int >& num){
    int n = sz(num), mid = n / 2;
    int i = mid - 1, j = (n % 2) ? mid + 1 : mid;
    bool leftsmaller = false;
    while (i >= 0 && num[i] == num[j])
        i--, j++;
    if (i < 0 || num[i] < num[j])
        leftsmaller = true;
    while (i >= 0){
        num[j++] = num[i--];
    }
    if (leftsmaller == true){
        int carry = 1;
        i = mid - 1;
        if (n % 2 == 1){
            num[mid] += carry;
            carry = num[mid] / 10;
            num[mid] %= 10;
            j = mid + 1;
        }
        else
            j = mid;
        while (i >= 0){
            num[i] += carry;
            carry = num[i] / 10;
            num[i] %= 10;
            num[j++] = num[i--];
        }
    }
}

void Solve(){
    string s;
    cin >> s;
    vector < int > num;
    for(auto &c : s)
        num.push_back(c - '0');
    if (is_all_nine(num, sz(num))){
        cout << 1;
        for(int i = 1; i < sz(num); ++i)
            cout << 0;
        cout << 1 << '\n';
    }
    else{
        get_next_palindrome(num);
        for(auto &x : num)
            cout << x;
        cout << '\n';
    }
}

int main(){
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    int test_cases = 1;
    // cin >> test_cases;
    for(int tc = 1; tc <= test_cases; tc++){
        // cout << "Case #" << tc << ": ";
        Solve();
    }
    return 0;
}