input: Write a python function to filter strings that have more than 3 characters from a comma-separated string.
  assert filter_strings("a,ab,abc,abcd,abcde") == ["abcd", "abcde"]
  assert filter_strings("one,two,three,four,five") == ["three", "four", "five"]
  assert filter_strings("hi,hello,yes,no") == ["hello"]
output: def filter_strings(s):
      return [word for word in s.split(',') if len(word) > 3]