#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
  vector<char> v1={'a','a','i','u','u','e'};
  vector<char> v2={'n','b','m','g','r'};
  vector<string> v3;
  for(int i=0;i<v1.size();++i){
    vector<char> v4=v1;
    char a=v4[i];
    v4.erase(v4.begin()+i);
    vector<char> v5=v2;
    do{
      do{
         string s1;
         for(int j=0;j<v5.size();++j){
           s1+=v5[j];
           s1+=v4[j];
         }
         for(int j=0;j<=s1.size();j+=2){
           string s2=s1;
           s2.insert(s2.begin()+j,a);
           v3.push_back(s2);
         }
      } while(next_permutation(v5.begin(),v5.end()));
    } while(next_permutation(v4.begin(),v4.end()));
  }
  int N;cin>>N;
  vector<string> v6;
  string S;
  for(int i=0;i<N;++i){
    cin>>S;
    v6.push_back(S);
  }
  for(int i=0;i<v3.size();++i){
    int f=0;
    for(int j=0;j<v6.size();++j){
      if(v3[i]==v6[j]){
        f=1;
        break;
      }
    }
    if(f==0){
      cout<<v3[i];
      break;
    }
  }
}