import re


def replace_http(url):
    """ Replace the http/https in a URL with www.
    >>> replace_http("http://google.com")
    www.google.com """
    data_regex = re.compile(r"^https?://")
    if data_regex.match(url) and "www." not in url:
        data = url.split("//")
        data[0] = "www."
        return ''.join(data)
    elif "www." in url:
        return url.split("//")[1]
    else:
        return url