#include <bits/stdc++.h>
using namespace std;

signed main(){
	int n;
	cin >> n;
	vector<tuple<int,int,int>> points;
	for(int t = 0;t < 2;t++){
		for(int i = 0;i < n;i++){
			int x,y;
			cin >> x >> y;
			points.emplace_back(x,y,t);
		}
	}
	sort(points.begin(),points.end());
	set<int> st;
	int ans = 0;
	for(int i = 0;i < n * 2;i++){
		int y,isBlue;
		tie(std::ignore,y,isBlue) = points[i];
		if(isBlue){
			auto it = st.lower_bound(y);
			if(it != st.begin()){
				it--;
				st.erase(it);
				ans++;
			}
		}else{
			st.insert(y);
		}
	}
	cout << ans << endl;
}
### Prompt

Your task is to create a Cpp solution to the following problem:

On a two-dimensional plane, there are N red points and N blue points. The coordinates of the i-th red point are (a_i, b_i), and the coordinates of the i-th blue point are (c_i, d_i).

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 \leq N \leq 100
* 0 \leq a_i, b_i, c_i, d_i < 2N
* a_1, a_2, ..., a_N, c_1, c_2, ..., c_N are all different.
* b_1, b_2, ..., b_N, d_1, d_2, ..., d_N are all different.

Input

Input is given from Standard Input in the following format:


N
a_1 b_1
a_2 b_2
:
a_N b_N
c_1 d_1
c_2 d_2
:
c_N d_N


Output

Print the maximum number of friendly pairs.

Examples

Input

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


Output

2


Input

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


Output

2


Input

2
2 2
3 3
0 0
1 1


Output

0


Input

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


Output

5


Input

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


Output

4

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;

signed main(){
	int n;
	cin >> n;
	vector<tuple<int,int,int>> points;
	for(int t = 0;t < 2;t++){
		for(int i = 0;i < n;i++){
			int x,y;
			cin >> x >> y;
			points.emplace_back(x,y,t);
		}
	}
	sort(points.begin(),points.end());
	set<int> st;
	int ans = 0;
	for(int i = 0;i < n * 2;i++){
		int y,isBlue;
		tie(std::ignore,y,isBlue) = points[i];
		if(isBlue){
			auto it = st.lower_bound(y);
			if(it != st.begin()){
				it--;
				st.erase(it);
				ans++;
			}
		}else{
			st.insert(y);
		}
	}
	cout << ans << endl;
}
```