#include <bits/stdc++.h>
using namespace std;
int n;
string S;
void solve() {
  sort(S.begin(), S.end());
  cout << S << "\n";
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  cin >> S;
  solve();
}
