import sys sys.setrecursionlimit(10 ** 6) from bisect import * from collections import * from heapq import * int1 = lambda x: int(x) - 1 p2D = lambda x: print(*x, sep="\n") def II(): return int(sys.stdin.readline()) def SI(): return sys.stdin.readline()[:-1] def MI(): return map(int, sys.stdin.readline().split()) def MI1(): return map(int1, sys.stdin.readline().split()) def MF(): return map(float, sys.stdin.readline().split()) def LI(): return list(map(int, sys.stdin.readline().split())) def LI1(): return list(map(int1, sys.stdin.readline().split())) def LF(): return list(map(float, sys.stdin.readline().split())) def LLI(rows_number): return [LI() for _ in range(rows_number)] dij = [(0, 1), (1, 0), (0, -1), (-1, 0)] def main(): def dfs(s="",aa=False,isa=True): if len(s)==11: if s in ss:return "" return s if isa: for i in range(5): if uses[i]:continue uses[i]=True ret=dfs(s+sc[i],aa,False) if ret:return ret uses[i]=False if (not isa) or (not aa): for i in range(6): if useb[i]:continue useb[i]=True ret=dfs(s+bc[i],aa|isa,True) if ret:return ret useb[i]=False return "" bc=['a','a','i','u','u','e'] sc=['n','b','m','g','r'] useb=[False]*6 uses=[False]*5 n=II() ss=set() for _ in range(n):ss.add(SI()) ans=dfs() if ans:print(ans) else:print("NO") main()