source_code: import java.io.BufferedReader;
  import java.io.BufferedWriter;
  import java.io.FileReader;
  import java.io.FileWriter;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.OutputStreamWriter;
  import java.io.StreamTokenizer;
  import java.lang.reflect.Array;
  import java.util.Arrays;
  
  
  public class a {
  
  	/**
  	 * @param args
  	 * @throws IOException 
  	 */
  	public static void main(String[] args) throws IOException {
  		// TODO Auto-generated method stub
  		//BufferedReader input = new BufferedReader(new FileReader("input.txt"));
  		//BufferedWriter output = new BufferedWriter(new FileWriter("output.txt"));
  		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
  		BufferedWriter output = new BufferedWriter(new OutputStreamWriter(System.out));
  		StreamTokenizer in = new StreamTokenizer(input);
  		
  		in.nextToken();
  		int n = (int)in.nval;
  		int[] mas = new int[n];
  		
  		for (int i = 0; i < n; i++) {
  			in.nextToken();
  			mas[i] = (int)in.nval;
  		}
  		
  		Arrays.sort(mas);
  		int min = mas[0];
  		int i = 1;
  		
  		while ((i < n)&&(min == mas[i])) {
  			i++;
  		}
  		
  		if (i < n) {
  			output.write(Integer.toString(mas[i]));
  		}
  		else {
  			output.write("NO");
  		}
  		input.close();
  		output.close();
  	}
  
  }
  