#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
const int N = 1e5 + 4;
int solve() {
  int n;
  scanf("%d", &n);
  string s;
  cin >> s;
  sort(s.begin(), s.end());
  cout << s;
  return 0;
}
int main() {
  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
