1)
code = '120300' 
index= len(code) - [i for i, item in enumerate(list(code[::-1])) if item != '0'][0] - 1
print(index)
2) 
code = '120300'
for i, char in enumerate(code[::-1]):
    if char != '0':
        index = i
        break
index = len(code) - index_border - 1
print(index)