#include<stdio.h>
int ispalindrome(int n)
{
    int reversed = 0,original = n, digits;
    while(n > 0){
        digits = n%10;
        reversed = reversed * 10+ digits;
        n/=10;
    }
    return(reversed == original);
}
int main(){
    float tempInput;
    int input;
    if(scanf("%f",&tempInput)!=1){
        printf("Invalid input");
        return 0;
    }
    intput = (int)tempInput;
    if(tempInput != input || input < 0){
        printf("Invalid input");
        return 0;
    }
    int next=input+1;
    while (!ispalindrome(next))
    {
        next++;
    }
    print("%d",next);
    return 0;
}