#include <bits/stdc++.h>
using namespace std;
char to_char(int a) { return a + 'a' - 1; }
int to_int(char a) { return a - 'a' + 1; }
int frek[30];
bool cmp(int a, int b) { return (frek[a] > frek[b]); }
bool cmp2(int a, int b) { return (frek[a] < frek[b]); }
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  string s;
  cin >> s;
  sort(s.begin(), s.end());
  cout << s << "\n";
  return 0;
  for (int i = 0; i < s.length(); i++) frek[to_int(s[i])]++;
  vector<int> ganjil, genap;
  for (int i = 1; i <= 26; i++) {
    if (frek[i] % 2 == 0)
      genap.push_back(i);
    else
      ganjil.push_back(i);
  }
  sort(ganjil.begin(), ganjil.end(), cmp);
  sort(genap.begin(), genap.end(), cmp);
  string gan, gen;
  string ans;
  ans = "";
  for (int i = 0; i < min(ganjil.size(), genap.size()); i++) {
    string tmp;
    tmp = "";
    if (abs(frek[ganjil[i]] - frek[genap[i]]) == 1) {
      if (frek[ganjil[i]] > frek[genap[i]]) {
        for (int j = 1; j <= frek[genap[i]]; j++) {
          tmp += (to_char(ganjil[i]));
          tmp += (to_char(genap[i]));
        }
        for (int j = 1; j <= frek[ganjil[i]] - frek[genap[i]]; j++)
          tmp += (to_char(ganjil[i]));
      } else {
        for (int j = 1; j <= frek[ganjil[i]]; j++) {
          tmp += (to_char(genap[i]));
          tmp += (to_char(ganjil[i]));
        }
        for (int j = 1; j <= frek[genap[i]] - frek[ganjil[i]]; j++)
          tmp += (to_char(genap[i]));
      }
    } else {
      for (int j = 1; j <= frek[ganjil[i]]; j++) tmp += (to_char(ganjil[i]));
      for (int j = 1; j <= frek[genap[i]]; j += 2) {
        tmp = tmp + (to_char(genap[i]));
        tmp = (to_char(genap[i])) + tmp;
      }
    }
    ans += tmp;
  }
  if (ganjil.size() < genap.size()) {
    string tmp;
    tmp = "";
    for (int i = ganjil.size(); i < genap.size(); i++) {
      for (int j = 1; j <= frek[genap[i]]; j += 2) {
        tmp = tmp + (to_char(genap[i]));
        tmp = (to_char(genap[i])) + tmp;
      }
    }
    ans = tmp + ans;
  } else {
    string tmp;
    tmp = "";
    for (int i = genap.size(); i < ganjil.size(); i++) {
      for (int j = 1; j <= frek[ganjil[i]]; j++) tmp += (to_char(ganjil[i]));
    }
    ans = tmp + ans;
  }
  cout << ans << "\n";
}
