#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n;
  char ary[100005];
  vector<pair<long long, char>> b;
  long long c[26];
  cin >> n;
  for (long long i = 0; i < n; i++) {
    cin >> ary[i];
  }
  sort(ary, ary + n);
  for (long long i = 0; i < n; i++) {
    cout << ary[i];
  }
  return 0;
}
