#include <bits/stdc++.h>
using namespace std;
bool palindrome(const string &s, int b, int e) {
  for (int i = 0; i < e - b + 1; i++)
    if (s[b + i] != s[e - i]) return false;
  return true;
}
int palindromity(const string &s) {
  int res = 0;
  for (int i = 0; i < s.length(); i++)
    for (int j = i; j < s.length(); j++)
      if (palindrome(s, i, j)) res++;
  return res;
}
string solve(string s) {
  int anspal = 0;
  string ans = s;
  do {
    int pal = palindromity(s);
    if (pal > anspal) {
      anspal = pal;
      ans = s;
    }
  } while (next_permutation(s.begin(), s.end()));
  return ans;
}
int main() {
  int n;
  string s;
  cin >> n >> s;
  sort(begin(s), end(s));
  cout << s;
}
