How many integer sequences A1, A2,…, AN of length N satisfy all of the following conditions? 0≤Ai≤9 There exists some such that Ai=0 holds. There exists some I such that Ai=9 holds. The answer can be very large, so output it modulo 10^9+7.

Explain this question please, and what should I learn to solve such types of questions?. Thank YOU