import java.util.*;
public class Main {
    public static void main (String [] args) {
        Scanner scn= new Scanner (System.in);
        
        int n = scn.nextInt();
        if (n<1) {
            System.out.print("Invalid input");
            return;
        }
        int arr [] = new int [n];
        for (int i=0; i<n; i++) {
            if (!scn.hasNextInt()) {
                System.out.print("Invalid input");
                return;
            }
            arr[i] = scn.nextInt();
            if (arr[i] <0) {
                System.out.pritn("Invalid input");
                return;
            }
        }
        
        int repeat =0;
        for (int i=0; i<n-1; i++) {
            for (int j=i+1; j<n; j++) {
                if (arr[i]==arr[j]) {
                    repeat = arr[j];
                }
            }
        }
        
        System.out.print(repeat);
    }
}