#include<iostream>
#include <bits/stdc++.h>
#include<string>
#include<algorithm>
using namespace std;
typedef pair<int,int> P;


int main(){
    int N;
    cin >> N;

    int a,b;
    vector<P> pr;
    for(int i=0;i<N;++i){
       cin >> a >> b;
       pr.push_back(P(b,a));
    }
    vector<P> pb;
    for(int i =0;i<N;++i){
        cin >>a >> b;
        pb.push_back(P(a,b));
    }
    sort(pr.begin(),pr.end());//yでソート
    sort(pb.begin(),pb.end());//xでソート
    int ans =0;

    for(int i=0;i<N;i++){
        for(int j=N-1;j >= 0;--j){
            if(pb.at(i).second > pr.at(j).first && pb.at(i).first > pr.at(j).second){
                ans++;
                pr.at(j)=P(2*N,2*N);
                break;
            }
        }

    }
    cout << ans <<endl;


}
### Prompt

Generate 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<iostream>
#include <bits/stdc++.h>
#include<string>
#include<algorithm>
using namespace std;
typedef pair<int,int> P;


int main(){
    int N;
    cin >> N;

    int a,b;
    vector<P> pr;
    for(int i=0;i<N;++i){
       cin >> a >> b;
       pr.push_back(P(b,a));
    }
    vector<P> pb;
    for(int i =0;i<N;++i){
        cin >>a >> b;
        pb.push_back(P(a,b));
    }
    sort(pr.begin(),pr.end());//yでソート
    sort(pb.begin(),pb.end());//xでソート
    int ans =0;

    for(int i=0;i<N;i++){
        for(int j=N-1;j >= 0;--j){
            if(pb.at(i).second > pr.at(j).first && pb.at(i).first > pr.at(j).second){
                ans++;
                pr.at(j)=P(2*N,2*N);
                break;
            }
        }

    }
    cout << ans <<endl;


}
```