#include <bits/stdc++.h>
using namespace std;
inline int in() {
  int x, y;
  y = scanf("%d", &x);
  return x;
}
const int N = -1;
int main() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  sort(s.begin(), s.end());
  cout << s << endl;
  return 0;
}
