#include <stdio.h>
#include <string.h>
#include <ctype.h>

// Function to check if a number is palindrome
int isPalindrome(int num) {
    int original = num, reversed = 0, digit;
    while (num > 0) {
        digit = num % 10;
        reversed = reversed * 10 + digit;
        num /= 10;
    }
    return (original == reversed);
}

// Function to check if string is a valid integer (no float, no symbols)
int isValidInteger(char str[]) {
    int len = strlen(str);
    for (int i = 0; i < len; i++) {
        if (!isdigit(str[i])) {
            return 0; // not valid integer
        }
    }
    return 1;
}

int main() {
    char input[50];
    int num;

    scanf("%s", input);

    // check if input is valid integer (not float, not chars)
    for (int i = 0; i < strlen(input); i++) {
        if (!isdigit(input[i])) {
            printf("Invalid input");
            return 0;
        }
    }

    num = atoi(input);

    // check negative or out of range
    if (num < 0 || num > 1000) {
        printf("Invalid input");
        return 0;
    }

    // find next palindrome
    int next = num + 1;
    while (1) {
        if (isPalindrome(next)) {
            printf("%d", next);
            break;
        }
        next++;
    }

    return 0;
}