#include <bits/stdc++.h>
using namespace std;
const long long MAXN = 2 * (1e3 + 1);
const long long INF = 1e18 + 1;
const long long MOD = 1e18 + 7;
const long long BITS = 64;
const long long PRIME = 31;
const long double EPS = 1e-12;
const long double PI = acos(-1);
void bye() {
  cout << "\n";
  exit(0);
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  string s;
  cin >> s;
  sort((s).begin(), s.end());
  cout << s;
  bye();
}
