#!/usr/bin/python2
from itertools import permutations, product
who = 'inabameguru'
m = len(who)
vow = set(map(''.join, permutations(who[::2])))
con = set(map(''.join, permutations(who[1::2])))
sett = set()
for p, q in product(con, vow):
    x = ''.join(map(''.join, zip(p, q[:-1])))
    for i in range(m):
        sett.add(x[:i] + q[-1] + x[i:])
n = int(raw_input())
s = set(raw_input() for _ in xrange(n))
sett -= s
res = 'NO'
if sett:
    res = sett.pop()
print(res)