第1行输入N,之后N行每行输入一对整数,描述一条道路.
输出宝藏的埋藏方式种数.
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
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.