本题来源于：2021 年 ICPC 亚洲（辽宁）沈阳区域赛
AAA gets a complete graph of vertices, where every pair of distinct vertices is connected by a unique edge, as a birthday present. However, AAA thinks the complete graph is not that beautiful and he decides to delete edges that form a tree.
Now he wonders the number of different perfect matchings in the remaining graph. Note that a perfect matching is a set of edges where no two edges share a common vertex. Since the answer may be very large, you only need to output the answer modulo .
The first line contains a single integer .
Each of the next lines contains two integers and , representing an edge deleted from the complete graph. It is guaranteed that the given edges form a tree of vertices.
Output a line containing a single integer, representing the answer modulo .
2 1 2 1 3 3 4
3 1 2 2 3 3 4 4 5 5 6