def read_file(file_name):
    """Read the input file into a list of lines."""
    try:
        with open(file_name, 'r') as f:
            read_lines = f.readlines()
    except FileNotFoundError:
        print("File could not be found. Please try again.")
        raise SystemExit(1)
    except PermissionError:
        print("Could not open file (insufficient privileges).")
        raise SystemExit(1)

    return read_lines