#include <bits/stdc++.h>
const int MAXINT = 2147483640;
const long long MAXLL = 9223372036854775800LL;
const long long MAXN = 1e6;
const double eps = 1e-9;
const long long mod = 1e9 + 7;
using namespace std;
long long a[MAXN], ans;
int main() {
  srand(time(0));
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  ;
  string s;
  long long n;
  cin >> n;
  cin >> s;
  sort(s.begin(), s.end());
  cout << s << "\n";
  return 0;
}
