Time Limit: 2000 mSec Memory Limit : 32768 KB

specialist in VLSI design testing must decide if there are some components
that cover each other for a given design. A component is represented as a rectangle.
Assume that each rectangle is rectilinearly oriented (sides parallel to the
x and y axis), so that the representation of a rectangle consists of its minimum
and maximum x and y coordinates.

Write a program that counts the rectangles that are entirely covered by another
rectangle.

The input contains the text description of several sets of rectangles.
The specification of a set consists of the number of rectangles in the set and
the list of rectangles given by the minimum and maximum x and y coordinates
separated by white spaces, in the format:

nr_rectangles

xmin1 xmax1 ymin1 ymax1

xmin2 xmax2 ymin2 ymax2

…

xminn xmaxn yminn ymaxn

The output should be printed on the standard output. For each given input data
set, print one integer number in a single line that gives the result (the number
of rectangles that are covered). An example is given in Figure 1.

3
100 101 100 101
0 3 0 101
20 40 10 400
4
10 20 10 20
10 20 10 20
10 20 10 20
10 20 10 20

0
4