#include <iostream>
#include <cstdio>
#include <string>
#include <algorithm>
#include <cmath>
#include <utility>
#include <vector>
#define rep(i, n) for(int i = 0; i < n; i++)
using namespace std;
typedef long long ll;

int N,ans=0;
bool used[100]={0};
pair<int,int> x[100],y[100];
int main() {
	cin>>N;
	for(int i=0;i<N;i++)cin>>x[i].first>>x[i].second;
	for(int i=0;i<N;i++)cin>>y[i].first>>y[i].second;
	sort(x,x+N);
	sort(y,y+N);
	for(int i=N-1;i>=0;i--){
		int k=999;
		int c=-1;
		for(int j=0;j<N;j++){
			if(x[i].first<y[j].first&&x[i].second<y[j].second&&k>y[j].second&&!used[j]){
				c=j;
				k=y[j].second;
			}
		}
		if(c!=-1){
			used[c]=1;
			ans++;	
		}
	}
	cout<<ans;
	return 0;
}
### Prompt

Develop a solution in CPP to the problem described below:

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 <iostream>
#include <cstdio>
#include <string>
#include <algorithm>
#include <cmath>
#include <utility>
#include <vector>
#define rep(i, n) for(int i = 0; i < n; i++)
using namespace std;
typedef long long ll;

int N,ans=0;
bool used[100]={0};
pair<int,int> x[100],y[100];
int main() {
	cin>>N;
	for(int i=0;i<N;i++)cin>>x[i].first>>x[i].second;
	for(int i=0;i<N;i++)cin>>y[i].first>>y[i].second;
	sort(x,x+N);
	sort(y,y+N);
	for(int i=N-1;i>=0;i--){
		int k=999;
		int c=-1;
		for(int j=0;j<N;j++){
			if(x[i].first<y[j].first&&x[i].second<y[j].second&&k>y[j].second&&!used[j]){
				c=j;
				k=y[j].second;
			}
		}
		if(c!=-1){
			used[c]=1;
			ans++;	
		}
	}
	cout<<ans;
	return 0;
}
```