#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int t = 0, n, e, x, y, z, i, j, k, g, q, ans = 0, sum = 0, c = 0, h;
  string s;
  cin >> n >> s;
  sort(s.begin(), s.end());
  cout << s;
  return 0;
}
