#include <bits/stdc++.h>
using namespace std;
using namespace std::chrono;
const long long INF = 1000 * 1000 * 1000 * 1ll * 1000 * 1000 * 1000;
string s[100005];
int cnt[10][1000005] = {0};
set<int> st[1000006];
vector<int> d, vv;
int main() {
  int n;
  map<char, int> mp;
  mp['a'] = 1;
  mp['i'] = 2;
  mp['o'] = 3;
  mp['e'] = 4;
  mp['u'] = 5;
  int count = 0, l;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> s[i];
    count = 0;
    for (int j = 0; j < s[i].length(); j++) {
      if (mp[s[i][j]] != 0) {
        count++;
        l = mp[s[i][j]];
      }
    }
    if (cnt[l][count] != 0) {
      d.push_back(cnt[l][count]);
      d.push_back(i);
      st[count].erase(cnt[l][count]);
      cnt[l][count] = 0;
    } else {
      cnt[l][count] = i;
      st[count].insert(i);
    }
  }
  vv.clear();
  for (int i = 1; i <= 1000000; i++) {
    for (auto it : st[i]) vv.push_back(it);
    if ((int)st[i].size() % 2 != 0) vv.pop_back();
  }
  if (vv.size() >= d.size()) {
    cout << d.size() / 2 << '\n';
    ;
    for (int i = 0; i < d.size(); i++) {
      cout << s[vv[i]] << " " << s[d[i]] << '\n';
    }
  } else {
    int diff = d.size() - vv.size();
    cout << vv.size() / 2 + diff / 4 << '\n';
    for (int i = 0; i < vv.size(); i++) {
      cout << s[vv[i]] << " " << s[d[i]] << '\n';
      ;
    }
    if (diff > 3) {
      for (int i = vv.size(); i + 3 < d.size(); i += 4) {
        cout << s[d[i]] << " " << s[d[i + 2]] << '\n';
        cout << s[d[i + 1]] << " " << s[d[i + 3]] << '\n';
      }
    }
  }
}
