public class Solution {

public static void main(String[] args) {

    int l = 0;
    int f1 = 100;
    int limit = 999;
    int f2 =0;
    int smallest = 0;
    int[] arr;

    Scanner in = new Scanner(System.in);
    l = in.nextInt();
    arr = new int[l];

    for (int i = 0; i < l; i++) {

// Pattern pttr = Pattern.compile("\d\d\d\d\d\d"); // Matcher m = pttr.matcher(String.valueOf()); // if (!m.matches()) { // // continue; // // } else { // // smallest = l; // //System.out.println(i); // //System.out.println(temp/i); // // // }

        arr[i]=in.nextInt();

    }

    for (int k = 0; k < 2; k++) {

        l=arr[k];

        while(true) {

            if(checkPalindrome(l)) {

                for(int i = f1 ; i<limit ; i++) {

                    if(l%i == 0) {



                        int temp = l;



                        Pattern pttr = Pattern.compile("\\d\\d\\d");
                        Matcher m = pttr.matcher(String.valueOf(temp/i));
                        if (!m.matches()) {

                            continue;

                        } else {

                            smallest = l;
                            //System.out.println(i);
                            //System.out.println(temp/i);


                        }


                        break;

                    }

                }

            }

            l=l-1;



            if (l<100000) {

                break;


            }

            if (smallest!=0) {

                break;

            }

        }

        System.out.println(smallest);
        smallest = 0;



    }





}



public static boolean checkPalindrome(int n) {

    String s = String.valueOf(n);

    if(s.charAt(0) == s.charAt(s.length()-1)) {

        int r = 0;
        int sum = 0;
        int temp = n;

        while (n>0) {

            r=n%10;  //getting remainder
            sum=(sum*10)+r;
            n=n/10;
        }

        if (temp == sum) {

            return true;
        }


    }

    return false;



}

}