Inquisition

题意翻译

# 题目描述 有一个正方形，长度为 $10^5$。 现在将正方形的左下角放入原点 $(0;0)$ 与右上角原点 $({10^5};{10^5})$ 于是，就构成了一个非退化的三角形。点可以重叠以及互相交叉。 且：保证一对三角形点的编不超出 $1$ 个公共点。 # 输入 第一行一个 $n(0 \leq n \leq 100)$ 。接下来 $n$ 行每行 $6$ 个整数： ${x_i},{y_i},{x_{2_i}},{y_{2_i}},{x_{3_i}},{y_{3_i}}$ 表示第 $i$ 三角形的坐标 $0 < x_{ji},y_{ji} < 10^{5}$。 # 输出 请输出三角形并集的周长。结果不得与正确答案相差超过 $10^{-6}$。

题目描述

In Medieval times existed the tradition of burning witches at steaks together with their pets, black cats. By the end of the 15-th century the population of black cats ceased to exist. The difficulty of the situation led to creating the EIC - the Emergency Inquisitory Commission. The resolution #666 says that a white cat is considered black when and only when the perimeter of its black spots exceeds the acceptable norm. But what does the acceptable norm equal to? Every inquisitor will choose it himself depending on the situation. And your task is to find the perimeter of black spots on the cat's fur. The very same resolution says that the cat's fur is a white square with the length of $ 10^{5} $ . During the measurement of spots it is customary to put the lower left corner of the fur into the origin of axes $ (0;0) $ and the upper right one — to the point with coordinates $ (10^{5};10^{5}) $ . The cats' spots are nondegenerate triangles. The spots can intersect and overlap with each other, but it is guaranteed that each pair of the triangular spots' sides have no more than one common point. We'll regard the perimeter in this problem as the total length of the boarders where a cat's fur changes color.

输入输出格式

输入格式

The first input line contains a single integer $ n $ ( $ 0<=n<=100 $ ). It is the number of spots on the cat's fur. The $ i $ -th of the last $ n $ lines contains $ 6 $ integers: $ x_{1i} $ , $ y_{1i} $ , $ x_{2i} $ , $ y_{2i} $ , $ x_{3i} $ , $ y_{3i} $ . They are the coordinates of the $ i $ -th triangular spot $ (0&lt;x_{ji},y_{ji}&lt;10^{5}) $ .

输出格式

Print a single number, the answer to the problem, perimeter of the union of triangles. Your answer should differ from the correct one in no more than $ 10^{-6} $ .

输入输出样例

输入样例 #1

1
1 1 2 1 1 2

输出样例 #1

3.4142135624

输入样例 #2

3
3 3 10 3 3 10
1 1 9 4 5 6
2 2 11 7 6 11

输出样例 #2

37.7044021497