def word_count(text):
    import re
    a = re.sub("[^А-Яа-я-A-Z-a-z ]", "", text)
    b = list(a)
    for i in b:
        c = b.count(i)
    return b


f = 'Я пришел, я ушел, я нашел'

print(word_count(f))