# The FME graph (2) P25513

Statement

thehtml

Lisbeth Salander (one of the main characters of the famous trilogy Millennium) is a crack mathematician, and therefore she is considering enrolling in the FME. As she likes both men and women, and she knows the FME graph, she is curious to know if it is possible that all the affairs have been between people of opposite sex. Help her!

Input

Input consists of several cases. Every case begins with the number of people n, followed by the information of each one: the name, the number mi of his or her affairs, and the mi names of the corresponding people. Assume that all the names are different, that for every pair of names x and y, if x is in the list of y then x exists and y is in the list of x, and that x is never in the list of x. Suppose 2 ≤ n ≤ 104, and that the total number of affairs is at most 2n.

Output

For every case, tell if it is possible that all the affairs have been between people of opposite sex.

Public test cases
• Input

```6
Alex 2 Felix Ivan
Enric 2 Ivan Felix
Ferran 1 Lander
Lander 1 Ferran
Ivan 2 Alex Enric
Felix 2 Enric Alex
4
a 0
d 2 b c
b 2 d c
c 2 d b
```

Output

```yes
no
```
• Information
Author
Ferran Alet i Ivan Geffner
Language
English
Translator
Original language
Catalan
Other languages
Catalan
Official solutions
C++
User solutions
C++