Today HH becomes a designer, and he faces a problem so he asks you for help. Treeisland is a country with n cities and n1 two-way road and from any city you can go to any other cities. HH the designer is going to design a plan to divide n city into n/2 pairs so that the sum of the length between the n/2 pairs city is minimum. Now HH has finished it but he doesn't know whether it's true so he ask you to calculate it together. It's guaranteed that n is even.
Today HH becomes a designer, and he faces a problem so he asks you for help. Treeisland is a country with n cities and n−1 two-way road and from any city you can go to any other cities. HH the designer is going to design a plan to divide n city into n/2 pairs so that the sum of the length between the n/2 pairs city is minimum. Now HH has finished it but he doesn't know whether it's true so he ask you to calculate it together. It's guaranteed that n is even.
（图片来源网络，侵删）
