There are n rectangles drawn on the plane. Each rectangle has sides parallel to the coordinate axes and integer coordinates of vertices.
We define a block as follows:

• each rectangle is a block,
• if two distinct blocks have a common segment then they form the new block otherwise we say that these blocks are separate.

Examples

The rectangles in Figure 1 form two separate blocks.

Figure 1

Task

Write a program that:

• reads the number of rectangles and coordinates of their vertices from the text file PRO.IN ;
• finds the number of separate blocks formed by the rectangles;
• writes the result to the text file PRO.OUT.

Input

In the first line of the input file PRO.IN there is an integer n, 1 <= n <=7000, which is the number of rectangles. In the following n lines there are coordinates of rectangles. Each rectangle is described by four numbers: coordinates x,y of the bottom-left vertex and coordinates x, y of the top-right vertex. All these coordinates are non-negative integers not greater than 10000.

Output

In the first and only line of the file PRO.OUT there should be written a single integer - the number of separate blocks formed by the given rectangles.

For the text file PRO.IN:

9
0 3 2 6
4 5 5 7
4 2 6 4
2 0 3 2
5 3 6 4
3 2 5 3
1 4 4 7
0 0 1 4
0 0 4 1

2