#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(inpuStr)){
        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;
}