传统题 1000ms 256MiB

C - Ubiquity

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C - Ubiquity

Score : $300$ points

Problem Statement

How many integer sequences $A_1,A_2,\ldots,A_N$ of length $N$ satisfy all of the following conditions?

  • $0 \leq A_i \leq 9$
  • There exists some $i$ such that $A_i=0$ holds.
  • There exists some $i$ such that $A_i=9$ holds.

The answer can be very large, so output it modulo $10^9 + 7$.

Constraints

  • $1 \leq N \leq 10^6$
  • $N$ is an integer.

Input

Input is given from Standard Input in the following format:

NN

Output

Print the answer modulo $10^9 + 7$.


2
2

Two sequences $\{0,9\}$ and $\{9,0\}$ satisfy all conditions.


1
0

869121
2511445

2024寒假入门组刷题营(十二)

未参加
状态
已结束
规则
ACM/ICPC
题目
8
开始于
2024-2-12 13:30
结束于
2024-2-12 15:30
持续时间
2 小时
主持人
参赛人数
10