#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 5;
int n;
struct node {
  int num, last;
  string str;
} s[N], s1[N], s2[N];
bool cmp(node a, node b) {
  return a.num > b.num || a.num == b.num && a.last < b.last;
}
int cnt1, cnt2, cnt3;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  for (int i = (1); i <= (n); i++) {
    cin >> s[i].str;
    int len = s[i].str.size();
    for (int j = (0); j <= (len - 1); j++) {
      if (s[i].str[j] == 'a')
        s[i].num++, s[i].last = 1;
      else if (s[i].str[j] == 'e')
        s[i].num++, s[i].last = 2;
      else if (s[i].str[j] == 'i')
        s[i].num++, s[i].last = 3;
      else if (s[i].str[j] == 'o')
        s[i].num++, s[i].last = 4;
      else if (s[i].str[j] == 'u')
        s[i].num++, s[i].last = 5;
    }
  }
  sort(s + 1, s + 1 + n, cmp);
  for (int i = (1); i <= (n); i++) {
    if (s[i].num == s[i + 1].num && s[i].last == s[i + 1].last && s[i].num &&
        s[i + 1].num) {
      s1[++cnt1] = s[i];
      s1[++cnt1] = s[i + 1];
      i++;
    } else if (s[i].num) {
      s2[++cnt2] = s[i];
    }
  }
  sort(s2 + 1, s2 + 1 + cnt2, cmp);
  for (int i = (1); i <= (cnt2); i++) {
    if (s2[i].num == s2[i + 1].num && s2[i].num) {
      s[++cnt3] = s2[i];
      s[++cnt3] = s2[i + 1];
      i++;
    }
  }
  cnt2 = cnt3;
  if (cnt2 >= cnt1)
    cout << cnt1 / 2;
  else
    cout << cnt2 / 2 + (cnt1 - cnt2) / 4;
  cout << endl;
  if (cnt2 >= cnt1) {
    for (int i = (1); i <= (cnt1); i++) {
      cout << s[i].str << " " << s1[i].str << endl;
      cout << s[i + 1].str << " " << s1[i + 1].str << endl;
      i++;
    }
  } else {
    for (int i = (1); i <= (cnt2); i++) {
      cout << s[i].str << " " << s1[i].str << endl;
      cout << s[i + 1].str << " " << s1[i + 1].str << endl;
      i++;
    }
    for (int i = (cnt2 + 1); i <= (cnt1); i++) {
      if (i + 3 > cnt1) break;
      cout << s1[i + 3].str << " " << s1[i].str << endl;
      cout << s1[i + 2].str << " " << s1[i + 1].str << endl;
      i += 3;
    }
  }
  return 0;
}
