#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;
    }
    scanf(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;
}