#!/usr/bin/python
from itertools import permutations, product, izip_longest
who = 'inabameguru'
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(nyaa, nykk):
    sett.add(''.join(map(lambda e: ''.join(e), izip_longest(*ele, fillvalue=''))))
n = int(raw_input())
s = set(raw_input() for _ in xrange(n))
sett -= s
if len(sett) > 0:
    print list(sett)[0]
else:
    print 'NO'