#include<stdio.h>
#include<string.h>
#include<ctype.h>
 int isPalindrome(int n) {
     int reversed = 0, original = n;
     }
    return original == reversed; 
 }
 int isValidNumber(char str[]) {
     int i = 0; 
     if (str[0] == '-') return 0;
     while (str[i]) {
         if (!isDigit(str[i]))
         return 0;
         i++;
     }
     return 1;
 }
 int main() {
     char inputStr[100];
     int naum;
     scanf("%s", InputStr);
     if (!isValidNumber(inputStr)) {
         printf("Invalid input\n");
         return 0;
     }
     sscanf(inputStr, "%d", &num);
     if (num < -1000 || num > 1000) {
         printf("Invalid input\n");
         return 0;
     }
     num++;
     while (1isPalindrom(num)) {
         num++;
     }
     printf("%d\n", num);
     return 0;
 }