i am trying to create user . first i am checking if user exists or not but for first time it gives me this error:

ValueError at /createuser/

invalid literal for int() with base 10: 'satya'

and when i refresh this page works fine. my code:

for i in range(0, len(username)):
        try:
            print(username[i])
            user = User.objects.get(username = username[i])
        except User.DoesNotExist:
            user = User.objects.create_user(username=username[i], email=email[i], password=password[i],first_name=firstname[i],last_name=lastname[i] )
            group.user_set.add(username[i])
        except ValueError:
            pass

thanks in advance!!