1714 - [Usaco2007 China]Treasure 财富

Input

第1行输入N，之后N行每行输入一对整数，描述一条道路．

Output

输出宝藏的埋藏方式种数．

Examples

Input

4
1 2
2 3
3 1
1 4

INPUT DETAILS:

Here is a drawing of the roads and the intersections.

4---1---2
\ /
3

Output

3

OUTPUT DETAILS:

The treasure can be buried at any intersection. However, burying it at
intersections 2 and 3 yields maps that are identical to each other. So the
total number of distinct treasure maps is 3.

Time Limit	1 second
Memory Limit	128 MB

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