Problem Statement

There are $N people numbered 1,2,\ldots,N$.
M parties were held. k_i people attended the $i-th (1\leq i \leq M)$ party, and they were People $x_{i,1},x_{i,2},\ldots,x_{i,k_i}$.
Determine if every two people attended the same party at least once.

Input

The input is given from Standard Input in the following format:
N M
$k_1 x_{1,1} x_{1,2} \ldots x_{1,k_1}$
$\vdots$
$k_M x_{M,1} x_{M,2} \ldots x_{M,k_M}$

Output

Print Yes if every two people attended the same party at least once; print No otherwise.

Constraints

• $2\leq N \leq 100$
• $1\leq M \leq 100$
• $2\leq k_i \leq N$
• $1\leq x_{i,1}<x_{i,2}<\ldots < x_{i,k_i}\leq N$
• All values in the input are integers.

Sample Input 1

3 3
2 1 2
2 2 3
2 1 3

Sample Output 1

Yes

Both Person 1 and Person 2 attended the 1-st party.
Both Person 2 and Person 3 attended the 2-nd party.
Both Person 1 and Person 3 attended the 3-rd party.
Therefore, every two people attended the same party at least once, so the answer is Yes.

Sample Input 2

4 2
3 1 2 4
3 2 3 4

Sample Output 2

No

Person 1 and Person 3 did not attend the same party, so the answer is No.

见题面 Input 部分

见题面 Output 部分