**Description **

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.

**Input **

**Output **

**Sample 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
```

**Sample Output **

```
0
4
```

**Hint **

Source: Southeastern Europe 2000