# 2785. hear tree

If a tree falls in the forest, and there’s nobody there to hear, does it make a sound? This classic conundrum was coined by George Berkeley (1685-1753), the Bishop and influential Irish philosopher whose primary philosophical achievement is the advancement of what has come to be called subjective idealism. He wrote a number of works, of which the most widely-read are Treatise Concerning the Principles of Human Knowledge (1710) and Three Dialogues between Hylas and Philonous (1713) (Philonous, the “lover of the mind,” representing Berkeley himself).

### 输入格式

In each testcase, a forest contains P people numbered from 1 to P and N trees numbered from 1 to N. Standard input consists of a line containing P and N and K followed by K lines, containing a pair of integers i and j, indicating that person i has heard tree j fall. People may have different opinions as to which trees, according to Berkeley, have made a sound. How many different opinions are represented in the input? Two people hold the same opinion only if they hear exactly the same set of trees. You may assume that P < 100 and N < 100.

### 输出格式

Output one line,with the answer described above;

### 样例

Input
1
3 4 6
1 2
3 3
1 3
2 2
3 2
2 4

Output
2


22 人解决，36 人已尝试。

28 份提交通过，共有 101 份提交。

5.4 EMB 奖励。