// editor5
import java.util.*;
public class main{
    public static void main(String[]args){
        Scanner S=new Scanner(System.in);
        int n=S.nextInt();
        if(n<2){
            System.out.println("Invalid input");
        }
        int arr[]=new int[n];
        for(int i=0;i<n;i++){
            arr[i]=S.nextInt();
        }
        Arrays.sort(arr);
        int larges=arr[n-1];
        int idx=n-2;
        while(idx>=0 && arr[idx]==largest)idx--;
        if(idx<0){
            System.out.println("Invalid input");
        }
        else{
            System.out.println(arr[idx]);
        }
    }
}