#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;

int main()
{
   ll n;

   cin>>n;

   ll a[n],b[n],c[n],d[n],ans=0;

   for(int i=0;i<n;i++) cin>>a[i]>>b[i];

   for(int i=0;i<n;i++) cin>>c[i]>>d[i];

   pair <ll , ll> red[n],blue[n];

   for(int i=0;i<n;i++)
   {
     red[i].first=b[i];
     red[i].second=a[i];
     blue[i].first=c[i];
     blue[i].second=d[i];
   }

   sort(red,red+n);
   sort(blue,blue+n);

   ll ch[111]={0};

   for(int i=0;i<n;i++)
   {
       for(int j=n-1;j>=0;j--)
       {
           if(red[j].second<blue[i].first && red[j].first<blue[i].second && ch[j]==0 )
           {
               ans++;
               ch[j]++;
               break;
           }
       }
   }

  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<bits/stdc++.h>
using namespace std;
typedef long long int ll;

int main()
{
   ll n;

   cin>>n;

   ll a[n],b[n],c[n],d[n],ans=0;

   for(int i=0;i<n;i++) cin>>a[i]>>b[i];

   for(int i=0;i<n;i++) cin>>c[i]>>d[i];

   pair <ll , ll> red[n],blue[n];

   for(int i=0;i<n;i++)
   {
     red[i].first=b[i];
     red[i].second=a[i];
     blue[i].first=c[i];
     blue[i].second=d[i];
   }

   sort(red,red+n);
   sort(blue,blue+n);

   ll ch[111]={0};

   for(int i=0;i<n;i++)
   {
       for(int j=n-1;j>=0;j--)
       {
           if(red[j].second<blue[i].first && red[j].first<blue[i].second && ch[j]==0 )
           {
               ans++;
               ch[j]++;
               break;
           }
       }
   }

  cout<<ans;
    return 0;
}

```