#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1);
const int oo = 1e9 + 10;
const int mod = 1e9 + 7;
const int N = 1e7 + 10;
void solve() {
  int n;
  scanf("%d", &n);
  string second;
  cin >> second;
  sort((second).begin(), (second).end());
  cout << second << endl;
}
int t;
int main() {
  solve();
  return 0;
}
