#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f, MOD = 1e9 + 7;
long long power(long long a, long long n) {
  long long p = 1;
  while (n > 0) {
    if (n % 2) {
      p = p * a;
    }
    n >>= 1;
    a *= a;
  }
  return p;
}
long long power(long long a, long long n, long long mod) {
  long long p = 1;
  while (n > 0) {
    if (n % 2) {
      p = p * a;
      p %= mod;
    }
    n >>= 1;
    a *= a;
    a %= mod;
  }
  return p % mod;
}
void swap(char *a, char *b) {
  char temp = *a;
  *a = *b;
  *b = temp;
}
long long int nCr(int n, int r) {
  long long int C[r + 1];
  memset(C, 0, sizeof(C));
  C[0] = 1;
  for (int i = 1; i <= n; i++) {
    for (int j = min(i, r); j > 0; j--) C[j] = (C[j] + C[j - 1]);
  }
  return C[r];
}
long long int countDer(int n) {
  int der[n + 1];
  der[0] = 1;
  der[1] = 0;
  der[2] = 1;
  for (int i = 3; i <= n; ++i) der[i] = (i - 1) * (der[i - 1] + der[i - 2]);
  return der[n];
}
int digitsum(long long a) {
  int ans = 0;
  while (a > 0) {
    ans = ans + a % 10;
    a = a / 10;
  }
  return ans;
}
int count(long long a) {
  int temp = 0;
  while (a > 0) {
    a = a / 10;
    temp++;
  }
  return temp;
}
int main() {
  int n;
  cin >> n;
  char s[n];
  for (int i = 0; i < n; i++) cin >> s[i];
  sort(s, s + n);
  for (int i = 0; i < n; i++) cout << s[i];
  cout << endl;
}
