#include<bits/stdc++.h>
using namespace std;
typedef pair<int,int> pi;
int main(){
	int n;
	cin>>n;
	vector<pair<pi,int> >arr;
	for(int i=0; i<n; i++){
		int x,y;
		cin>>x>>y;
		arr.push_back(make_pair(pi(x,y),0));
	}
	for(int i=0; i<n; i++){
		int x,y;
		cin>>x>>y;
		arr.push_back(make_pair(pi(x,y),1));
	}
	sort(arr.begin(),arr.end());
	int ret = 0;
	int y_coord[505]={0};
	for(int i=0; i<arr.size(); i++){
		if(arr[i].second==0) y_coord[arr[i].first.second]++;
		else{
			int y = arr[i].first.second;
			for(int j=y-1; j>=0; j--){
				if(y_coord[j]){
					ret++;
					y_coord[j]--;
					break;
				}
			}
		}
	}
	cout<<ret;
}
### Prompt

Construct a CPP code solution to the problem outlined:

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;
typedef pair<int,int> pi;
int main(){
	int n;
	cin>>n;
	vector<pair<pi,int> >arr;
	for(int i=0; i<n; i++){
		int x,y;
		cin>>x>>y;
		arr.push_back(make_pair(pi(x,y),0));
	}
	for(int i=0; i<n; i++){
		int x,y;
		cin>>x>>y;
		arr.push_back(make_pair(pi(x,y),1));
	}
	sort(arr.begin(),arr.end());
	int ret = 0;
	int y_coord[505]={0};
	for(int i=0; i<arr.size(); i++){
		if(arr[i].second==0) y_coord[arr[i].first.second]++;
		else{
			int y = arr[i].first.second;
			for(int j=y-1; j>=0; j--){
				if(y_coord[j]){
					ret++;
					y_coord[j]--;
					break;
				}
			}
		}
	}
	cout<<ret;
}
```