#include <iostream>
#include <vector>
#include <set>
#include <string>

using namespace std;

void make_cand(set<string>& cand, vector<string>& shiin, vector<string>& boin, int pos, vector<string> cur){
    if(pos >= 6){
        string res;
        for(int i = 0; i < cur.size(); i++){
            res += cur[i];
        }
        cand.insert(res);
        return;
    }
    for(int i = 0; i < shiin.size(); i++){
        for(int j = 0; j < boin.size(); j++){
            cur.push_back(shiin[i]);
            cur.push_back(boin[j]);
            shiin.erase(shiin.begin() + i);
            boin.erase(boin.begin() + j);
            make_cand(cand, shiin, boin, pos+1, cur);
            boin.insert(boin.begin() + j, cur.back());
            cur.pop_back();
            shiin.insert(shiin.begin() + i, cur.back());
            cur.pop_back();
        }
    }
}


int main(){
    vector<string> shiin;
    shiin.push_back("");
    shiin.push_back("n");
    shiin.push_back("b");
    shiin.push_back("m");
    shiin.push_back("g");
    shiin.push_back("r");
    vector<string> boin;
    boin.push_back("i");
    boin.push_back("a");
    boin.push_back("a");
    boin.push_back("e");
    boin.push_back("u");
    boin.push_back("u");

    set<string> cand;
    vector<string> cur;
    make_cand(cand, shiin, boin, 0, cur);
    
    int N;
    cin >> N;
    for(int i = 0; i < N; i++){
        string s;
        cin >> s;
        cand.erase(s);
    }
    if(cand.empty()){
        cout << "NO" << endl;
    }else{
        cout << *cand.begin() << endl;
    }
    return 0;
}