rbpoints

Title

Problem Statement

On a two-dimensional plane, there are N red points and N blue points. The coordinates of the i-th red point are (ai, bi), and the coordinates of the i-th blue point are (ci, di).

A red point and a blue point can form a friendly pair when, the x-coordinate of the red point is smaller than that of the blue point, and the y-coordinate of the red point is also smaller than that of the blue point.

At most how many friendly pairs can you form? Note that a point cannot belong to multiple pairs.

Constraints

  • All input values are integers.
  • 1 ≤ N ≤ 1000000
  • 0 ≤ ai, bi, ci, di < 2N
  • a1, a2, ..., aN, c1, c2, ..., cN are all different.
  • b1, b2, ..., bN, d1, d2, ..., dN are all different.

Input

Input is given from Standard Input in the following format:

N
a1 b1
a2 b2
:
aN bN
c1 d1
c2 d2
:
cN dN

Output

Print the maximum number of friendly pairs.

Sample Input 1

3
2 0
3 1
1 3
4 2
0 4
5 5

Sample Output 1

2

For example, you can pair (2, 0) and (4, 2), then (3, 1) and (5, 5).

Sample Input 2

3
0 0
1 1
5 2
2 3
3 4
4 5

Sample Output 2

2

For example, you can pair (0, 0) and (2, 3), then (1, 1) and (3, 4).

Sample Input 3

2
2 2
3 3
0 0
1 1

Sample Output 3

0

It is possible that no pair can be formed.

Sample Input 4

5
0 0
7 3
2 2
4 8
1 6
8 5
6 9
5 4
9 1
3 7

Sample Output 4

5

Sample Input 5

5
0 0
1 1
5 5
6 6
7 7
2 2
3 3
4 4
8 8
9 9

Sample Output 5

4

Submitting .cpp to 'rbpoints'


You're not logged in! Click here to login

Time Limit: 2 Seconds
Memory Limit: 1024MB
No. of ACs: 3
Your best score: 0
Source: ABC 091C

Subtask Score
1 100
2 0