create a 20 digit string, and cast to a list then add all the digits as integers

[nikhilkumar]

my question here
create a 20 digit string, and cast to a list
then add all the digits as integers
print the equation and answer
Hint: use cast to sum the digits, and .join() to create the equation (1+2+3+...)

new_digit="20,10,70,30,20"
print(list(new_digit))
sum_of_digits=0
new_digit=int(new_digit)
for digits in new_digit:
   #digits=int(digits)
   sum_of_digits+=digits
print("+".join(new_digit))

But I am getting ValueError: invalid literal for int() with base 10: '20,10,70,30,20'