определить длину кратчайшей последовательности
aa, bb = [], []
for c, k in zip('СБТРЙТБОЙЁЛМЯШЁК',
[12, 10, 21, 7, 19, 25, 14, 3, 5, 26, 30, 23, 11, 9, 20, 13]):
i = 'АБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ'.index(c)
aa.append((i + k) % 33)
bb.append((i - k) % 33)
print(aa) # [30, 11, 7, 24, 29, 11, 15, 18, 15, 32, 9, 3, 10, 1, 26, 24]
print(bb) # [6, 24, 31, 10, 24, 27, 20, 12, 5, 13, 15, 23, 21, 16, 19, 31]