#include <iostream>
#include <string>
#include <sstream>
using namespace std;

// Helper function to check if a number is palindrome
bool is_palindrome(int n) {
    string s = to_string(n);
    int l = 0, r = s.length()-1;
    while (l < r) {
        if (s[l] != s[r])
            return false;
        l++;
        r--;
    }
    return true;
}

int main() {
    string input;
    getline(cin, input);
    // Check for numeric and non-negative input
    int n;
    stringstream ss(input);
    if (!(ss >> n) || n < 0 || ss.rdbuf()->in_avail() != 0) {
        cout << "Invalid input" << endl;
        return 0;
    }
    // Find next palindrome
    int next = n + 1;
    while (!is_palindrome(next)) {
        next++;
    }
    cout << next << endl;
    return 0;
}