#include <bits/stdc++.h>
using namespace std;
long long mypow(long long a, long long b) {
  if (b == 0) return 1;
  long long temp = mypow(a, b / 2);
  temp = (temp * temp) % 1000000007LL;
  if (b % 2 == 1) temp = (a * temp) % 1000000007LL;
  return temp;
}
int mygcd(int a, int b) {
  if (b == 0) return a;
  return mygcd(b, a % b);
}
int cntBits(long long a) {
  int ret = 0;
  while (a > 0) {
    ret++;
    a /= 2;
  }
  return ret;
}
int main() {
  ios::sync_with_stdio(0);
  int n;
  cin >> n;
  string s;
  cin >> s;
  sort(s.begin(), s.end());
  cout << s << endl;
  return 0;
}
