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

бн

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.

**Input**

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

**Output**

0 4