#include <bits/stdc++.h>
using namespace std;
const int inf = (int)1e9;
const int mod = inf + 7;
const double eps = 1e-9;
const double pi = acos(-1.0);
long long read_long() {
  long long ans = 0;
  char c;
  bool started = false;
  bool is_negative = false;
  while (true) {
    c = getchar();
    if ((c < '0' || c > '9') && c != '-' && !started) continue;
    if ((c < '0' || c > '9') && c != '-' && started) break;
    if (started) {
      ans = ans * 10;
    }
    started = true;
    if (c == '-')
      is_negative = true;
    else
      ans += c - '0';
  }
  if (is_negative) ans *= -1;
  return ans;
}
int n;
char tmp[100100];
int main() {
  scanf("%d\n%s", &n, tmp);
  sort(tmp, tmp + n);
  cout << tmp << endl;
  return 0;
}
