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

syntax has to be unambiguous and also backward compatible.

If auto is dropped there will be no way to distinguish between statements and definitions.

auto n = 0; // fine
n=0; // statememt, n is undefined.