# External Rectangles

On a plane, there are n rectangles drawn, each with vertices at integer coordinates and sides parallel to the coordinate axes. The boundaries of any two rectangles do not overlap. This means that any two rectangles are either completely separate or one is entirely contained within the other. In this context, some rectangles are considered "external," meaning they are not contained within any other rectangle, while the others are "internal." Your task is to determine the number of "external" rectangles.

## Input

The first line contains the integer n (1 ≤ n ≤ 10^5). Each of the following n lines contains four integers x_1, y_1, x_2, y_2 (-10^9 ≤ x_1, y_1, x_2, y_2 ≤ 10^9), representing the coordinates of two opposite vertices of the rectangle.

## Output

Print a single number: the count of "external" rectangles.