Need help guys!

Error: AttributeError: 'str' object has no attribute 'sort'

brand_name = "Huawei"
count = 3
 while count <= 3:
    brands = str(input(" Enter cellphone brandname:"))
    brand_name.insert(brands, count)
    count = 1 + count
brand_name.sort()
brand_name.remove("Huawei")
print(brand_name)