#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <vector>
#include <string>
using namespace std;
const int maxn=1e4+5;

struct node
{
	int x;
	int y;
	bool vis;
}red[maxn],blue[maxn];

bool cmp(node n1,node n2)
{
    return n1.x < n2.x;
}

int main()
{
	int n;
	cin>>n;
	for(int i=0;i<n;i++)
	{
		cin>>red[i].x>>red[i].y;
		red[i].vis=0;
	}
		
	for(int i=0;i<n;i++)
	{
		cin>>blue[i].y>>blue[i].x;
		blue[i].vis=0;
	}
	sort(red,red+n,cmp);
	sort(blue,blue+n,cmp);
	int i=0,j=0,ans=0;
	
	for(i=n-1;i>=0;i--)
	{
		for(j=0;j<n;j++)
		{
			if(blue[j].vis) continue;
			if(blue[j].x>red[i].y&&blue[j].y>red[i].x)
			{
			
				blue[j].vis=1;
				ans++;
				break;
			}
		}
	}
	cout<<ans<<endl;
}
### 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 <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <vector>
#include <string>
using namespace std;
const int maxn=1e4+5;

struct node
{
	int x;
	int y;
	bool vis;
}red[maxn],blue[maxn];

bool cmp(node n1,node n2)
{
    return n1.x < n2.x;
}

int main()
{
	int n;
	cin>>n;
	for(int i=0;i<n;i++)
	{
		cin>>red[i].x>>red[i].y;
		red[i].vis=0;
	}
		
	for(int i=0;i<n;i++)
	{
		cin>>blue[i].y>>blue[i].x;
		blue[i].vis=0;
	}
	sort(red,red+n,cmp);
	sort(blue,blue+n,cmp);
	int i=0,j=0,ans=0;
	
	for(i=n-1;i>=0;i--)
	{
		for(j=0;j<n;j++)
		{
			if(blue[j].vis) continue;
			if(blue[j].x>red[i].y&&blue[j].y>red[i].x)
			{
			
				blue[j].vis=1;
				ans++;
				break;
			}
		}
	}
	cout<<ans<<endl;
}
```