import re

def find_longest_path(paths):
    ms = 0
    mp = None
    for path in paths:
        s = len(path)
        if s > ms:
            ms = s
            mp = path
    return mp

def find_shortest_path(paths):
    ms = float('inf')
    mp = None
    for path in paths:
        s = len(path)
        if s < ms:
            ms = s
            mp = path
    return mp

def find_common_ancestor(paths):
    if len(paths) == 0:
        return None

    shortest_path = find_shortest_path(paths)
    
    last_common = None
    for gen_i,_ in enumerate(shortest_path):
        common = True
        last_node = paths[0][gen_i]

        for path in paths:
            if last_node == path[gen_i]:
                common = True
                last_node = path[gen_i]
            else:
                common = False
        if common:
            last_common = last_node
    return last_common

def comment_remover(text):
    def replacer(match):
        s = match.group(0)
        if s.startswith('/'):
            return ""
        else:
            return s
    pattern = re.compile(
        r'//.*?$|/\*.*?\*/|\'(?:\\.|[^\\\'])*\'|"(?:\\.|[^\\"])*"',
        re.DOTALL | re.MULTILINE
    )
    return re.sub(pattern, replacer, text)