B'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. The first line contains a single integer n (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89n xe2 x80 x89 xe2 x89 xa4 xe2 x80 x895). Next n lines contain four integers each, describing a single rectangle: x1, y1, x2, y2 (0 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89x1 xe2 x80 x89< xe2 x80 x89x2 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x8931400, xe2 x80 x890 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89y1 xe2 x80 x89< xe2 x80 x89y2 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x8931400) -- x1 and x2 are x-coordinates of the left and right edges of the rectangle, and y1 and y2 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). In a single line print "YES", if the given rectangles form a square, or "NO" otherwise.'...