Connect Three

题意翻译

给出A,B,C三点坐标，用最短的路径把他们连起来，输出路径上的点。

题目描述

The Squareland national forest is divided into equal $ 1 \times 1 $ square plots aligned with north-south and east-west directions. Each plot can be uniquely described by integer Cartesian coordinates $ (x, y) $ of its south-west corner. Three friends, Alice, Bob, and Charlie are going to buy three distinct plots of land $ A, B, C $ in the forest. Initially, all plots in the forest (including the plots $ A, B, C $ ) are covered by trees. The friends want to visit each other, so they want to clean some of the plots from trees. After cleaning, one should be able to reach any of the plots $ A, B, C $ from any other one of those by moving through adjacent cleared plots. Two plots are adjacent if they share a side. For example, $ A=(0,0) $ , $ B=(1,1) $ , $ C=(2,2) $ . The minimal number of plots to be cleared is $ 5 $ . One of the ways to do it is shown with the gray color.Of course, the friends don't want to strain too much. Help them find out the smallest number of plots they need to clean from trees.

输入输出格式

输入格式

The first line contains two integers $ x_A $ and $ y_A $ — coordinates of the plot $ A $ ( $ 0 \leq x_A, y_A \leq 1000 $ ). The following two lines describe coordinates $ (x_B, y_B) $ and $ (x_C, y_C) $ of plots $ B $ and $ C $ respectively in the same format ( $ 0 \leq x_B, y_B, x_C, y_C \leq 1000 $ ). It is guaranteed that all three plots are distinct.

输出格式

On the first line print a single integer $ k $ — the smallest number of plots needed to be cleaned from trees. The following $ k $ lines should contain coordinates of all plots needed to be cleaned. All $ k $ plots should be distinct. You can output the plots in any order. If there are multiple solutions, print any of them.

输入输出样例

输入样例 #1

0 0
1 1
2 2

输出样例 #1

5
0 0
1 0
1 1
1 2
2 2

输入样例 #2

0 0
2 0
1 1

输出样例 #2

4
0 0
1 0
1 1
2 0

说明

The first example is shown on the picture in the legend. The second example is illustrated with the following image: 

题意翻译

给出A,B,C三点坐标，用最短的路径把他们连起来，输出路径上的点。