#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) __typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii; typedef long long ll;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }

const char *str = "inabameguru";
const int len = strlen(str);
bool vowel[128];
int cnt[128];
char curstr[20];
int num;
set<string> prohibit;
string ans;
void searchall(int i, bool v) {
	if(i == len) {
		if(!v) return;
		curstr[i] = 0;
		if(!prohibit.count(curstr)) {
			ans = curstr;
		}
		return;
	}
	rep(a, 26) if(cnt['a' + a] > 0) {
		char c = 'a' + a;
		if(!v && !vowel[c]) continue;
		curstr[i] = c;
		-- cnt[c];
		searchall(i + 1, vowel[c]);
		++ cnt[c];
		if(!ans.empty()) return;
	}
}

int main() {
	vowel['a'] = vowel['e'] = vowel['i'] = vowel['o'] = vowel['u'] = true;
	for(const char *p = str; *p; ++ p)
		++ cnt[*p];
	int N;
	while(~scanf("%d", &N)) {
		prohibit.clear();
		string S;
		rep(i, N) {
			cin >> S;
			prohibit.insert(S);
		}
		ans = "";
		searchall(0, true);
		if(ans.empty())
			puts("NO");
		else
			cout << ans << endl;
	}

	return 0;
}