#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;
}