Can't input zero in my code

Question

From this code, why can't I input the number 0. So I want when I input a number in front of or behind a 0, the value will be replaced by the number entered, but after that I can input another 0 behind it because it is for calculations. For example, if I input 10, then only the number 1 is entered, the number 0 is not entered
https://code.sololearn.com/W8qd5QZ7s73E/?ref=app

Answer 1

Code is throwing an error on line 36

Answer 2

this code is not running. check and upload it again. If not here, then share github link.