source_code: import java.util.*;
  import java.lang.*;
  import java.io.*;
  
  public class Blah
  {
      public static void main(String args[])
      {
  	Scanner c = new Scanner(System.in);
  	String number = c.nextLine();
  	int i = Integer.parseInt(number);
  	if (i == 1)
  	    {
  		System.out.println("NO");
  		return;
  	    }
  	String line = c.nextLine();
  	String[] arr = line.split(" ");
  	int[] array = new int[i];
  	for (int j = 0; j < i; j++)
  	    {
  		array[j] = Integer.parseInt(arr[j]);
  	    }
          int min = array[0];
  	int second = 0;
  	boolean thing = false;
  	for (int j = 0; j < i; j++)
  	    {
  		if (!thing && array[j] > min)
  		    {
  			second = array[j];
  			thing = true;
  		    }
  		if (array[j] < min)
  		    {
  			second = min;
  			min = array[j];
  			thing = true;
  		    }
  		else if (thing && array[j] > min && array[j] < second)
  		    second = array[j];
  	    }
  	if (!thing)
  	    System.out.println("NO");
  	else
  	    System.out.println(second);
  	return;	     
      }
  }