CF325A.Square and Rectangles

You are given n rectangles. The corners of rectangles have integer coordinates and their edges are parallel to the Ox and Oy axes. The rectangles may touch each other, but they do not overlap (that is, there are no points that belong to the interior of more than one rectangle).

Your task is to determine if the rectangles form a square. In other words, determine if the set of points inside or on the border of at least one rectangle is precisely equal to the set of points inside or on the border of some square.

给你 $n$ 个矩形。每个矩形的顶点坐标均为整数，且其边分别与 $Ox$ 轴和 $Oy$ 轴平行。这些矩形可以相互接触，但不能重叠（即不存在属于多于一个矩形内部的点）。

你的任务是判断这些矩形是否构成一个正方形。换言之，判断所有位于至少一个矩形内部或边界上的点所组成的集合，是否恰好等于某个正方形内部或边界上的点所组成的集合。

The first line contains a single integer n (1 ≤ n ≤ 5). Next n lines contain four integers each, describing a single rectangle: _x_1, _y_1, _x_2, _y_2 (0 ≤ _x_1 < _x_2 ≤ 31400, 0 ≤ _y_1 < _y_2 ≤ 31400) — _x_1 and _x_2 are x-coordinates of the left and right edges of the rectangle, and _y_1 and _y_2 are y-coordinates of the bottom and top edges of the rectangle.

No two rectangles overlap (that is, there are no points that belong to the interior of more than one rectangle).

第一行包含一个整数 $n$（$1 \leq n \leq 5$）。接下来的 $n$ 行每行包含四个整数，描述一个矩形：$x_1, y_1, x_2, y_2$（$0 \leq x_1 < x_2 \leq 31400$，$0 \leq y_1 < y_2 \leq 31400$）——其中 $x_1$ 和 $x_2$ 分别为该矩形左、右边界在 $x$ 轴上的坐标，$y_1$ 和 $y_2$ 分别为该矩形下、上边界在 $y$ 轴上的坐标。

任意两个矩形互不重叠（即不存在属于多于一个矩形内部的点）。

In a single line print "YES", if the given rectangles form a square, or "NO" otherwise.

如果给定的矩形能构成一个正方形，则在一行中输出 “YES”，否则输出 “NO”。