A simple program in Python for renaming multiple files that checks and it does not overwrite old files that match to our pattern

renamer.py

from os import rename, path, listdir

try:
    path_of_dir = input('Enter path of directory with your file:')
    ext = input('Print file extension (unquoted) (".jpg" for example):')
    list_of_filename = listdir(path_of_dir)
    count = 1
    for file in list_of_filename:
        full_old_name = path.join(path_of_dir, file)
        new_name = "{:0>6}".format(count) + ext
        while new_name in list_of_filename:
            count += 1
            new_name = "{:0>6}".format(count) + ext
        full_new_name = path.join(path_of_dir, new_name)
        rename(full_old_name, full_new_name)
        count += 1

except FileNotFoundError:
    print("Invalid path of directory. You must write valid path\
    \nfor example: 'F:/somedirectory' for windows or '/home/usr/somedirectory' for linux)")

except Exception as e:
    print(f'Error {e}')

else:
    print('Renaming completed successfully')