#include <bits/stdc++.h>
using namespace std;
const long double pi = 4 * atan((long double)1);
const long long mod = 1e9 + 7;
const long long inf = 922337203685477;
const long long nax = 0;
long long n;
string s;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n >> s;
  sort(s.begin(), s.end());
  cout << s << '\n';
}
