Split Characters As Lines in File

[quest_]

Hello,
I have this txt file. (The length is 15000)
1010100101010110000000000001111111111
And according to input, I want to separate my numbers as different lines and each line will have equal size
For instance, suppose that i is the input and i =10
then my text file will become like that:
1010100101
0101011000
0000000000...

The code should be something like that

with open("names.txt","r") as f:
    input_list = f.read()    

def write_len(input_list):
    final_str = "\n".join([str(len(item)) for item in input_list])

    with open("name_length.txt","w") as w:
        w.write(final_str)

    return 1

But I couldn't complete it
Can you please help me?
Best