#include<stdio.h>
#include<stdlib.h>
int is_palindrome(int main){
    int original = num, reversed = 0;
    while(num > 0){
        reversed = reversed * 10 + num % 10;
        num /=10;
    }
    return(original == reversed);
}
int next_palindrome(int n){
    while(1){
        n++;
        if(is_palindrome(n)){
            return n;
        }
    }
}
int main(){
    int num;
    if(scanf("%d",&num)!= 1){
        printf("Invalid Input");
        return 0;
    }
    if(num< 0){
        printf("Invalid Input");
        return 0;
    }
    printf("%d",next_palindrome(num));
    return 0;
}