import itertools
def popcount(x):
    x = x - ((x >> 1) & 0x55555555)
    x = (x & 0x33333333) + ((x >> 2) & 0x33333333)
    x = (x + (x >> 4)) & 0x0f0f0f0f
    x += x >> 8
    x += x >> 16
    return x & 0x0000003f

S = "iaaeuu"
bo = set()
for ss in itertools.permutations(S):
    bo.add("".join(ss))
S = "nbmgr"
shi = set()
for ss in itertools.permutations(S):
    shi.add("".join(ss))
bits = []
for bit in range(1 << 11):
    pc = popcount(bit)
    if pc != 5:
        continue
    if bit >> 10 & 1:
        continue
    ok = True
    for i in range(10):
        if bit >> i & 1 and bit >> (i + 1) & 1:
            ok = False
            break
    if ok:
        bits.append(bit)

se = set()
for S in bo:
    for T in shi:
        for bit in bits:
            X = []
            sp = 0
            tp = 0
            for i in range(11):
                if bit >> i & 1:
                    X.append(T[tp])
                    tp += 1
                else:
                    X.append(S[sp])
                    sp += 1
            se.add("".join(X))

n = int(input())
for _ in range(n):
    S = input()
    se.remove(S)

for s in se:
    print(s)
    exit()
print("NO")