#include <bits/stdc++.h>
using namespace std;
bool palindrome(string s) {
  int n = s.length();
  for (int i = 0; i < n; i++) {
    if (s[i] != s[n - i - 1]) return 0;
  }
  return 1;
}
int main() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  sort(s.begin(), s.end());
  cout << s << endl;
  return 0;
}
