#include <bits/stdc++.h>
using namespace std;
void solve() {
  int i, j, k, m, n, ans = 0, cnt = 0;
  cin >> n;
  string s;
  cin >> s;
  sort(s.begin(), s.end());
  cout << s << endl;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  solve();
  return 0;
}
