CF14C.Four Segments

Several months later Alex finally got his brother Bob's creation by post. And now, in his turn, Alex wants to boast about something to his brother. He thought for a while, and came to the conclusion that he has no ready creations, and decided to write a program for rectangles detection. According to his plan, the program detects if the four given segments form a rectangle of a positive area and with sides parallel to coordinate axes. As Alex does badly at school and can't write this program by himself, he asks you to help him.

几个月后，亚历克斯终于通过邮局收到了他弟弟鲍勃的创作。现在，轮到亚历克斯向弟弟炫耀点什么了。他思考了一阵子，得出结论：自己手头没有任何现成的作品，于是决定编写一个矩形检测程序。根据他的设想，该程序需判断给定的四条线段是否能构成一个面积为正、且边与坐标轴平行的矩形。由于亚历克斯学业不佳，无法独立编写此程序，因此他请求你帮助他。

The input data contain four lines. Each of these lines contains four integers _x_1, _y_1, _x_2, _y_2 ( - 109 ≤ _x_1, _y_1, _x_2, _y_2 ≤ 109) — coordinates of segment's beginning and end positions. The given segments can degenerate into points.

输入数据包含四行。每行包含四个整数 $x_1$, $y_1$, $x_2$, $y_2$（其中 $-10^9 \le x_1, y_1, x_2, y_2 \le 10^9$），表示线段起点和终点的坐标。所给线段可能退化为点。

Output the word «YES», if the given four segments form the required rectangle, otherwise output «NO».

如果给定的四条线段能构成所要求的矩形，则输出单词 «YES»，否则输出 «NO»。