Say Hello

题意翻译

## **题目描述** 两个朋友正在芭比星系旅行。他们说“你好啊！”如果距离小于或等于d1且 ·这是他们第一次交谈，或者 ·在他们上次谈话后的某个时间点，他们的距离大于d2。 我们需要计算朋友们说“你好”的次数。彼此之间。对于n个时刻，您将为每个朋友提供一组点，代表他们在那一时刻的位置。一个人可以在两个时刻之间保持相同的位置，但是如果一个人移动了，我们假设这个移动是以恒定的速度在恒定的方向上移动。 ## 输入输出格式 输出包含一个整数，表示朋友彼此之间会说“你好啊！”的次数。

题目描述

Two friends are travelling through Bubble galaxy. They say "Hello!" via signals to each other if their distance is smaller or equal than $ d_1 $ and - it's the first time they speak to each other or - at some point in time after their last talk their distance was greater than $ d_2 $ . We need to calculate how many times friends said "Hello!" to each other. For $ N $ moments, you'll have an array of points for each friend representing their positions at that moment. A person can stay in the same position between two moments in time, but if a person made a move we assume this movement as movement with constant speed in constant direction.

输入输出格式

输入格式

The first line contains one integer number $ N $ ( $ 2 \leq N \leq 100\,000 $ ) representing number of moments in which we captured positions for two friends. The second line contains two integer numbers $ d_1 $ and $ d_2 \ (0 < d_1 < d_2 < 1000) $ . The next $ N $ lines contains four integer numbers $ A_x,A_y,B_x,B_y $ ( $ 0 \leq A_x, A_y, B_x, B_y \leq 1000 $ ) representing coordinates of friends A and B in each captured moment.

输出格式

Output contains one integer number that represents how many times friends will say "Hello!" to each other.

输入输出样例

输入样例 #1

4
2 5
0 0 0 10
5 5 5 6
5 0 10 5
14 7 10 5

输出样例 #1

2

说明

 Explanation: Friends should send signals 2 times to each other, first time around point $ A2 $ and $ B2 $ and second time during A's travel from point $ A3 $ to $ A4 $ while B stays in point $ B3=B4 $ .

题意翻译

## **题目描述** 两个朋友正在芭比星系旅行。他们说“你好啊！”如果距离小于或等于d1且 ·这是他们第一次交谈，或者 ·在他们上次谈话后的某个时间点，他们的距离大于d2。 我们需要计算朋友们说“你好”的次数。彼此之间。对于n个时刻，您将为每个朋友提供一组点，代表他们在那一时刻的位置。一个人可以在两个时刻之间保持相同的位置，但是如果一个人移动了，我们假设这个移动是以恒定的速度在恒定的方向上移动。 ## 输入输出格式 输出包含一个整数，表示朋友彼此之间会说“你好啊！”的次数。