#include <bits/stdc++.h>
using namespace std;
void solve();
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed;
  cout.precision(20);
  solve();
  return 0;
}
template <typename T>
void chmin(T& a, T b) {
  if (a > b) a = b;
}
template <typename T>
void chmax(T& a, T b) {
  if (a < b) a = b;
}
template <typename T>
void MACRO_rdv2_Init(int n, T& t) {
  t.resize(n);
}
template <typename First, typename... Rest>
void MACRO_rdv2_Init(int n, First& first, Rest&... rest) {
  first.resize(n);
  MACRO_rdv2_Init(n, rest...);
}
template <typename T>
void MACRO_rdv2_Scan(int p, T& t) {
  std::cin >> t[p];
}
template <typename First, typename... Rest>
void MACRO_rdv2_Scan(int p, First& first, Rest&... rest) {
  std::cin >> first[p];
  MACRO_rdv2_Scan(p, rest...);
}
template <typename T>
void wrv(const vector<T>& v) {
  for (int(__ii) = (0); (__ii) < (((int)v.size())); ++(__ii)) {
    if (__ii) cout << ' ';
    cout << v[__ii];
  }
  cout << '\n';
}
template <typename T>
void wrm(const vector<vector<T>>& v) {
  for (int(__ii) = (0); (__ii) < (((int)v.size())); ++(__ii)) {
    for (int(__jj) = (0); (__jj) < (v[__ii].size()); ++(__jj)) {
      if (__jj) cout << ' ';
      cout << v[__ii][__jj];
    }
    cout << '\n';
  }
}
template <typename T>
void sc(T& x) {
  cin >> x;
}
template <typename Head, typename... Tail>
void sc(Head& head, Tail&... tail) {
  cin >> head;
  sc(tail...);
}
template <typename T>
void wr(const T& x) {
  cout << x << '\n';
}
template <typename Head, typename... Tail>
void wr(const Head& head, const Tail&... tail) {
  cout << head << ' ';
  wr(tail...);
}
template <typename T>
void wrf(const T& x) {
  cout << x << endl;
}
template <typename Head, typename... Tail>
void wrf(const Head& head, const Tail&... tail) {
  cout << head << ' ';
  wrf(tail...);
}
template <typename T>
void debug_out(const T& x) {
  cerr << x << '\n';
}
template <typename Head, typename... Tail>
void debug_out(const Head& head, const Tail&... tail) {
  cerr << head << ' ';
  debug_out(tail...);
}
template <typename... T>
void err(const T&... cod) {
  wr(cod...);
  exit(0);
}
const int ALPHA = 555;
int n;
string s;
vector<string> v;
int cnt[ALPHA];
int p = 0;
bool can(int cur) {
  int len = n / cur;
  return p >= len / 2 * cur;
}
void construct(int cur) {
  int len = n / cur;
  v.resize(cur);
  for (int(i) = (0); (i) < (cur); ++(i)) v[i].resize(len);
  int p = 0;
  for (int(i) = (0); (i) < (cur); ++(i)) {
    for (int(j) = (0); (j) < (len / 2); ++(j)) {
      while (cnt[p] < 2) ++p;
      v[i][j] = v[i][len - 1 - j] = p;
      cnt[p] -= 2;
    }
  }
  p = 0;
  for (int(i) = (0); (i) < (cur); ++(i)) {
    if (len % 2 == 1) {
      while (!cnt[p]) ++p;
      v[i][len / 2] = p;
      --cnt[p];
    }
  }
}
void upd(int& ans, int len) {
  int cur = n / len;
  if (can(cur)) chmin(ans, cur);
}
void solve() {
  cin >> n >> s;
  for (int(i) = (0); (i) < (n); ++(i)) ++cnt[s[i]];
  for (int(i) = (0); (i) < (ALPHA); ++(i)) p += cnt[i] / 2;
  int ans = n;
  for (int(len) = (1); (len) < (n + 1); ++(len)) {
    if (n % len == 0) {
      upd(ans, len);
    }
  }
  construct(ans);
  wr(ans);
  wrv(v);
}
