#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int num;
  bool flag = true;
  int* numbers = new int[n];
  for (int i = 0; i < n; i++) {
    cin >> num;
    numbers[i] = num;
    if (i == n - 1) break;
  }
  for (int i = 0; i < n - 1; i++)
    for (int j = i + 1; j < n; j++) {
      if (numbers[i] > numbers[j]) swap(numbers[i], numbers[j]);
    }
  int s;
  if (n == 1)
    flag = false;
  else {
    for (int i = 0; i < n; i++) {
      if (numbers[i] > numbers[0]) {
        flag = true;
        s = numbers[i];
        break;
      }
      flag = false;
    }
  }
  if (flag)
    cout << s << endl;
  else
    cout << "NO";
  return 0;
}
