source_code: import java.util.*; 
   
  public class Main 
  { 
   public static void main(String[] args) 
   { 
    Scanner keyboard = new Scanner(System.in); 
    int size = keyboard.nextInt(); 
    int[] arr = new int[size]; 
    int i = 0; 
    while( size != 0 ) 
    {  
     arr[i] = keyboard.nextInt(); 
     size--;  
     i++; 
    } 
     //System.out.print("size " + arr.length );
     Arrays.sort(arr); 
   
     int index = 0; 
     boolean val = false; 
     int ans = 0; 
     for ( i = 0; i< arr.length-1 ; i++ ) 
     { 
      //System.out.print(" arr[i] " + arr[i] + " arr[i+1] " + arr[i+1] + "\n" );
      if( arr[i] != arr[i+1] ) 
      { 
       val = true; 
       //System.out.print("Changed val to true");
       index = i+1; 
        System.out.println(arr[index]); 
        return; 
      } 
     } 
       
      if (size == 1 || ( val == false))
      { 
          System.out.println("NO");    
      } 
   
      
   } 
    
  }