#include <bits/stdc++.h>
using namespace std;
template <typename P, typename Q>
ostream& operator<<(ostream& os, pair<P, Q> p) {
  os << "(" << p.first << "," << p.second << ")";
  return os;
}
template <typename P, typename Q>
istream& operator>>(istream& is, pair<P, Q>& p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T>
ostream& operator<<(ostream& os, vector<T> v) {
  os << "(";
  for (auto& i : v) os << i << ",";
  os << ")";
  return os;
}
template <typename T>
istream& operator>>(istream& is, vector<T>& v) {
  for (auto& i : v) is >> i;
  return is;
}
int f(string s) {
  int cnt = 0;
  for (int i = 0; i < s.size(); ++i) {
    for (int j = 0; j <= s.size(); ++j) {
      string t;
      for (int k = i; k < j; ++k) {
        t += s[k];
      }
      if (t.size()) {
        string u = t;
        reverse(u.begin(), u.end());
        cnt += (t == u);
      }
    }
  }
  return cnt;
}
void fn() {
  cout << f("ghghghg") << ' ' << f("gggghhh") << endl;
  cout << f("llooo") << ' ' << f("ololo") << endl;
  cout << f("gagadbcgghhchbdf") << ' ' << f("abccbaghghghgdfd") << ' '
       << f("aabbccddfgggghhh") << endl;
}
int main(int argc, char* argv[]) {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n;
  string s;
  while (cin >> n >> s) {
    sort(s.begin(), s.end());
    cout << s << endl;
  }
  return 0;
}
