#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;
    }
    input = (int)tempinput;
    if(tempinput != input || input<0){
        printf("Invalid input");
        return 0;
    }
    int next=input+1;
    while(ispalindrome(next)){
        next++;
    }
    pritnf("%d", next);
}