def sum_of_digits(s):
only_numbers = "+".join(filter(lambda x: x.isdigit(), s))
only_letters = "".join(filter(lambda x: not x.isdigit(), s))
total_numbers = sum(tuple(map(int, only_numbers.split('+'))))
print(f"The extracted non-digits are: {only_letters}", end="\n\n")
print(f"The sum of digits operation performs {only_numbers} = {total_numbers}")
sum_of_digits("e12aw4")