题目描述
Problem Statement
There are $M sets, called S_1, S_2, \dots, S_M,$ consisting of integers between 1 and N.
S_i consists of $C_i integers a_{i, 1}, a_{i, 2}, \dots, a_{i, C_i}$.
There are (2^M-1) ways to choose one or more sets from the M sets.
How many of them satisfy the following condition?
- For all integers x such that $1 \leq x \leq N,$ there is at least one chosen set containing x.
Input
The input is given from Standard Input in the following format:
N M
C_1
$a_{1,1} a_{1,2} \dots a_{1,C_1}$
C_2
$a_{2,1} a_{2,2} \dots a_{2,C_2}$
$\vdots$
C_M
$a_{M,1} a_{M,2} \dots a_{M,C_M}$
Output
Print the number of ways to choose sets that satisfy the conditions in the Problem Statement.
Constraints
- $1 \leq N \leq 10$
- $1 \leq M \leq 10$
- $1 \leq C_i \leq N$
- $1 \leq a_{i,1} \lt a_{i,2} \lt \dots \lt a_{i,C_i} \leq N$
- All values in the input are integers.
Sample Input 1
3 3
2
1 2
2
1 3
1
2
Sample Output 1
3
The sets given in the input are $S_1 = \lbrace 1, 2 \rbrace, S_2 = \lbrace 1, 3 \rbrace, S_3 = \lbrace 2 \rbrace$.
The following three ways satisfy the conditions in the Problem Statement:
- choosing S_1, S_2;
- choosing S_1, S_2, S_3;
- choosing S_2, S_3.
Sample Input 2
4 2
2
1 2
2
1 3
Sample Output 2
0
There may be no way to choose sets that satisfies the conditions in the Problem Statement.
Sample Input 3
6 6
3
2 3 6
3
2 4 6
2
3 6
3
1 5 6
3
1 3 6
2
1 4
Sample Output 3
18
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分