# include "bits/stdc++.h"
using namespace std;
using LL = long long;
using ULL = unsigned long long;
const double PI = acos(-1);
template<class T>constexpr T INF() { return ::std::numeric_limits<T>::max(); }
template<class T>constexpr T HINF() { return INF<T>() / 2; }
template <typename T_char>T_char TL(T_char cX) { return tolower(cX); };
template <typename T_char>T_char TU(T_char cX) { return toupper(cX); };
typedef pair<LL, LL> pii;
const int vy[] = { -1, -1, -1, 0, 1, 1, 1, 0 }, vx[] = { -1, 0, 1, 1, 1, 0, -1, -1 };
const int dx[4] = { 0,1,0,-1 }, dy[4] = { 1,0,-1,0 };
int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; }
int d_sum(LL n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; }
int d_cnt(LL n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; }
LL gcd(LL a, LL b) { if (b == 0)return a; return gcd(b, a%b); };
LL lcm(LL a, LL b) { LL g = gcd(a, b); return a / g*b; };
# define ALL(qpqpq)           (qpqpq).begin(),(qpqpq).end()
# define UNIQUE(wpwpw)        sort(ALL((wpwpw)));(wpwpw).erase(unique(ALL((wpwpw))),(wpwpw).end())
# define LOWER(epepe)         transform(ALL((epepe)),(epepe).begin(),TL<char>)
# define UPPER(rprpr)         transform(ALL((rprpr)),(rprpr).begin(),TU<char>)
# define FOR(i,tptpt,ypypy)   for(LL i=(tptpt);i<(ypypy);i++)
# define REP(i,upupu)         FOR(i,0,upupu)
# define INIT                 std::ios::sync_with_stdio(false);std::cin.tie(0)

vector<int> v = {0, 1, 2, 3, 4, 5};
string vs = "iaaeuu";
vector<int> v2 = {0, 1, 2, 3, 4, 5};
string v2s = "nbmgr\0";

int n;
string s[202020];
vector<string> t;

int main(){
    INIT;
    cin >> n;
    REP(i, n){
        cin >> s[i];
    }
    if(n == 0){
        cout << "inabameguru" << endl;
        return 0;
    }
    sort(s, s + n);
    do{
        do{
            string ss = "";
            ss = ss + (char)v2s[v[0]] + (char)vs[v2[0]] + (char)v2s[v[1]] + (char)vs[v2[1]] + (char)v2s[v[2]] + (char)vs[v2[2]] + (char)v2s[v[3]] + (char)vs[v2[3]] + (char)v2s[v[4]] + (char)vs[v2[4]] + (char)v2s[v[5]] + (char)vs[v2[5]];
            string sss = "";
            REP(i,(int)ss.size())if(ss[i] != '\0')sss += ss[i];
            t.emplace_back(sss);
        }while(next_permutation(ALL(v2)));
    }while(next_permutation(ALL(v)));

    sort(ALL(t));
    UNIQUE(t);
    REP(i, n){
        if(s[i] != t[i]){
            cout << t[i] << endl;
            return 0;
        }
    }
    cout << "NO" << endl;
}