#include <algorithm>
#include <complex>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rrep(i, n) for (int i = (n)-1; i >= 0; i--)
using namespace std;
typedef long long int lli;
typedef pair<lli, lli> P;
lli MOD = 1000000007;
int main()
{
    char mt[6] = {'i', 'a', 'a', 'e', 'u', 'u'};
    char pa[5] = {'m', 'g', 'r', 'n', 'b'};

    sort(mt, mt + 6);
    sort(pa, pa + 5);
    set<string> s;
    int n;
    cin >> n;
    string t;
    rep(i, n)
    {
        cin >> t;
        s.insert(t);
    }
    do {
        do {
            string tmp = "..........";
            rep(i, 5) tmp[2 * i + 1] = mt[i];
            rep(i, 5) tmp[2 * i] = pa[i];
            rep(i, 9)
            {
                string a = tmp;
                string b{mt[5]};
                a.insert(i + 1, b);
                if (s.find(a) == s.end()) {
                    cout << a << endl;
                    return 0;
                }
            }
        } while (next_permutation(pa, pa + 5));
    } while (next_permutation(mt, mt + 6));
}