Hints

LM-C06-C-001

Count only the exact token a.

LM-C06-C-002

Look for adjacent pairs, not individual words.

LM-C06-C-003

Use count(context, next) / count(context).

LM-C06-C-004

An n-gram has n - 1 context tokens.

LM-C06-C-005

If the context never appears, no following token is observed after it.