#include <bits/stdc++.h>
using namespace std;
const int N = 2 * 1e5 + 10;
const long long inf = 1e18 + 100;
const long long mod = 1e9 + 7;
void solve() {
  long long n;
  cin >> n;
  string s;
  cin >> s;
  sort(s.begin(), s.end());
  cout << s << "\n";
}
int main() {
  long long t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
