#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
int const lmt = 1e5 + 5;
long long int a[26];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long int n;
  cin >> n;
  string second, ans = "";
  cin >> second;
  sort((second).begin(), (second).end());
  cout << second << "\n";
  return 0;
}
