#include <bits/stdc++.h>
const char dl = '\n';
const long double eps = 0.00000001;
const long long MOD = 1e9 + 7;
const double PI = 3.141592653589793238463;
using namespace std;
void debug() { cout << endl; }
template <typename H, typename... T>
void debug(H p, T... t) {
  std::cout << p << " ";
  debug(t...);
}
string second, t, q;
long long ans;
int n, m, k;
int cnt[30];
int main() {
  fflush(stdin);
  cout << fixed, cout.precision(18);
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int i, j;
  cin >> n >> second;
  sort(second.begin(), second.end());
  cout << second;
}
