Why do I need to explicitly write the 'auto' keyword?

Question

I am moving towards C++11 from C++98 and have become familiar with the auto keyword. I was wondering why we need to explicitly declare auto if the

Answer 1

Dropping the explicit auto would break the language:

e.g.

int main()
{
    int n;
    {
        auto n = 0; // this shadows the outer n.
    }
}

where you can see that dropping the auto would not shadow the outer n.