#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long n, i, j, k, l, m, a, b, t, sum, sum1, flag;
  string s, s1;
  cin >> n;
  cin >> s;
  sort(s.begin(), s.end());
  cout << s << endl;
}
