#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n;
  cin >> n;
  vector<char> t;
  string s;
  cin >> s;
  for (long long i = 0; i < n; ++i) {
    t.push_back(s[i]);
  }
  sort(t.begin(), t.end());
  for (long long i = 0; i < n; ++i) {
    cout << t[i];
  }
  return 0;
}
