source_code: import java.io.BufferedReader;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.io.StreamTokenizer;
  import java.util.ArrayDeque;
  import java.util.Arrays;
  
  
  public class Main {
  	private static StreamTokenizer in;
  	private static PrintWriter out;
  	
  	private static int nextInt() throws Exception {
  		in.nextToken();
  		return (int)in.nval;
  	}
  	
  	private static String nextString() throws Exception {
  		in.nextToken();
  		return in.sval;
  	}
  	
  	public static void main(String[] args) throws Exception {
  		in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
  		out = new PrintWriter(System.out);
  		
  		int n = nextInt();
  		int[] a = new int[n];
  		for (int i=0; i<n; i++)
  			a[i] = nextInt();
  		Arrays.sort(a);
  		int u = a[0];
  		for (int i=0; i<n; i++)
  			if (a[i]>u) {
  				out.println(a[i]);
  				out.flush();
  				return;
  			}
  		out.println("NO");
  		out.flush();
  	}
  }
  