#! /usr/bin/env python3

charsets = [
    ['А', 'а', 'aa'],
    ['Е', 'е', 'и', ''],
]

def gen(word, char_index):
    if char_index < len(charsets):
        for i in range(len(charsets[char_index])):
            gen(word + charsets[char_index][i], char_index + 1)
    else:
        print(word)

gen('', 0)