source_code: import java.io.*;
  import java.util.*;
  import static java.lang.Math.*;
  
  public class Solution {
  
      BufferedReader in;
      PrintWriter out;
      StringTokenizer st;
  
      void solve() throws IOException {
          int n = ni();
          int[] v = new int[n];
          for (int i = 0; i < n; ++i)
              v[i] = ni();
          Arrays.sort(v);
          int mn = v[0];
          for (int i = 1; i < n; ++i)
              if (v[i] > mn) {
                  out.println(v[i]);
                  return;
              }
          out.println("NO");
      }
  
      public Solution() throws IOException {
          Locale.setDefault(Locale.US);
          in = new BufferedReader(new InputStreamReader(System.in));
          out = new PrintWriter(System.out);
          solve();
          in.close();
          out.close();
      }
  
      String ns() throws IOException {
          while (st == null || !st.hasMoreTokens()) {
              st = new StringTokenizer(in.readLine());
          }
          return st.nextToken();
      }
  
      int ni() throws IOException {
          return Integer.valueOf(ns());
      }
  
      long nl() throws IOException {
          return Long.valueOf(ns());
      }
  
      double nd() throws IOException {
          return Double.valueOf(ns());
      }
  
      public static void main(String[] args) throws IOException {
          new Solution();
      }
  }
  