#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
const long long modx = 998244353;
const long long Nx = 1e5 + 2;
const long long inf = (long long)(1e19 + 10LL);
void solve() {
  long long n;
  cin >> n;
  string str;
  cin >> str;
  sort(str.begin(), str.end());
  cout << str << endl;
}
signed main() {
  long long test = 1;
  while (test--) {
    solve();
  }
  return 0;
}
