#!/usr/bin/env python

import sys

filename = sys.argv[1]

with open(filename, "r") as fileobj:
    data = fileobj.read()

    max_linelength = 0
    for line in data.splitlines():
        max_linelength = max(max_linelength, len(line))

print(f"The longest line has a length of {max_linelength}.")