#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 inuputstr[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", num);
    return 0;
}