#include <bits/stdc++.h>
using namespace std;
int arr[30];
int main() {
  string s;
  int n;
  cin >> n;
  cin >> s;
  for (int i = 0; i < s.size(); i++) arr[s[i] - 'a']++;
  sort(s.begin(), s.end());
  cout << s << endl;
  return 0;
}
