#!/usr/bin/python
# -*- coding: utf-8 -*-
from itertools import permutations, product, izip_longest
who = 'inabameguru'
n = len(who)
nya = ''.join(who[i] for i in xrange(0, len(who), 2))
nyk = ''.join(who[i] for i in xrange(1, len(who), 2))
nyaa = {''.join(e) for e in permutations(nya)}
nykk = {''.join(e) for e in permutations(nyk)}
sett = set()
for ele in product(nykk, nyaa):
    x = ''.join(map(lambda e: ''.join(e), zip(ele[0], ele[1][:-1])))
    for i in xrange(n):
        y = x[:i] + ele[1][-1] + x[i:]
        sett.add(y)
n = int(raw_input())
s = set(raw_input() for _ in xrange(n))
sett -= s
print (list(sett) + ['NO'])[0]