#include <bits/stdc++.h>
using namespace std;
const int MAXR = 1000005;
int fact[1000000];
int inv[1000000];
long long binpow(int a, int b, int m) {
  a %= m;
  long long res = 1;
  while (b > 0) {
    if (b & 1) res = (res * a) % m;
    a = ((a % m) * (a % m)) % m;
    b >>= 1;
  }
  return res;
}
void cal1() {
  fact[0] = 1;
  for (int i = 1; i < 1000000; i++) {
    fact[i] = (fact[i - 1] * i) % 1000000007;
  }
  for (int i = 0; i < 1000000; i++) {
    inv[i] = binpow(fact[i], 1000000007 - 2, 1000000007);
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n;
  cin >> n;
  string s;
  cin >> s;
  sort(s.begin(), s.end());
  cout << s;
}
