#include <bits/stdc++.h>
using namespace std;
inline int read() {
  int x = 0, f = 1;
  char ch;
  for (ch = getchar(); !isdigit(ch); ch = getchar())
    if (ch == '-') f = -f;
  for (; isdigit(ch); ch = getchar()) x = 10 * x + ch - '0';
  return x * f;
}
int n;
char s[111000];
int a[111000];
int main() {
  n = read();
  scanf("%s", s + 1);
  for (int i = 1; i <= n; i++) a[i] = s[i] - 'a';
  sort(a + 1, a + n + 1);
  for (int i = 1; i <= n; i++) cout << (char)(a[i] + 'a');
}
