#include <bits/stdc++.h>
using namespace std;
void vout(vector<long long> ans) {
  for (auto ele : ans) cout << ele << " ";
  cout << endl;
}
vector<long long> adj[200001];
bool vis[200001];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cout.precision(8);
  cout << fixed;
  long long n;
  cin >> n;
  string s;
  cin >> s;
  sort(s.begin(), s.end());
  cout << s;
  return 0;
}
