#include <stdio.h>
#include <string.h>
#include <ctype.h>
int ispalindrome(int n)  {
    int reversed = 0, original = n;
    while (n > 0){
        reversed = reversed * 10 + (n % 10);
        n /= 10;
    }
    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 num;
     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 (!isPalindrome(num)){
    num++;
  }
printf("%d\n", num);
return 0;
  }