import itertools

se = set()
T = []
used = [False] * 11
S = "inamameguru"
T = []
bo = set(["i", "a", "e", "u"])
def dfs(t):
    if t == 11:
        if T[-1] in bo:
            se.add("".join(T))
            return
    for i in range(11):
        if used[i]:
            continue
        if t != 0 and T[-1] not in bo and S[i] not in bo:
            continue
        T.append(S[i])
        used[i] = True
        dfs(t + 1)
        T.pop()
        uesd[i] = False


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

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