#include <bits/stdc++.h>
using namespace std;
const int maxn = 500050;
const int maxc = 256;
char s[maxn];
int cnt[maxc];
deque<char> res, ov, prt;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n >> s;
  for (int i = 0; i < n; ++i) ++cnt[s[i]];
  int oc = 0, dc;
  for (int i = 0; i < maxc; ++i)
    if (cnt[i] & 1) {
      ++oc;
      ov.push_back(i);
    }
  for (int i = 0; i < maxc; ++i)
    for (int j = 0; j < cnt[i] / 2; ++j) res.push_back(i);
  if (oc) {
    for (dc = oc; dc <= n; dc += 2) {
      if (n % dc == 0 && res.size() % dc == 0) break;
      ov.push_back(res[0]);
      ov.push_back(res[0]);
      res.pop_front();
    }
    assert(dc <= n);
    int cc = n / dc;
    cout << dc << '\n';
    for (int i = 0; i < dc; ++i) {
      prt.clear();
      for (int j = 0; j < cc / 2; ++j) {
        cout << res[0];
        prt.push_back(res[0]);
        res.pop_front();
      }
      cout << ov[0];
      ov.pop_front();
      for (int j = prt.size() - 1; j >= 0; --j) cout << prt[j];
      cout << " \n"[i == dc - 1];
    }
  } else {
    cout << "1\n";
    for (char ch : res) cout << ch;
    reverse(res.begin(), res.end());
    for (char ch : res) cout << ch;
    cout << '\n';
  }
}
