#include <bits/stdc++.h>

using namespace std;

const int N = 27;

bool h[N];

int add(string std)
{
  int a = 0;
  if (std.find("l") != string::npos) a = 10;
  if (std.find("la") != string::npos) a = 20;
  if (std.find("lan") != string::npos) a = 30;
  if (std.find("lanq") != string::npos) a = 40;
  if (std.find("lanqi") != string::npos) a = 50;
  if (std.find("lanqio") != string::npos) a = 60;
  if (std.find("lanqiob") != string::npos) a = 70;
  if (std.find("lanqiobe") != string::npos) a = 80;
  return a;
}

int main()
{
  // 请在此输入您的代码
  int n;
  string st;
  cin >> n >> st;

  // cout << n << st;
  // for (int i = 0; i < n; i ++ ) cout << st[i];
  string res;
  int Max = 0;
  for (int i = 0; i < n; i ++ )
  {
    memset(h, 0, sizeof h);
    string ty;
    ty += st[i];
    h[st[i] - 'a'] = true;
    int tk = (st[i] - 'a') + 1;
    int j = i + 1;

    while (j < n && !h[st[j] - 'a'])
    {
      tk += st[j] - 'a' + 1;
      h[st[j] - 'a'] = true;
      ty += st[j ++ ];
    }
    tk += add(ty);

    if (tk >= Max)
    {
      if (tk == Max && ty.compare(res) < 0)
      {
        res = ty;
      }
      else if (tk > Max)
      {
        Max = tk;
        res = ty;
      }
    }
  }

  cout << res << endl;
  return 0;
}