#include<iostream>
#include<cstring>
#include<vector>
#include<algorithm>

#define P pair<int, int>

using namespace std;

int main(){
  int n, a, b, check[109];
  memset(check, 0 , sizeof(check));
  cin >> n;
  vector<P> v1, v2;
  for(int i=0;i<n;i++){
    cin >> a >> b;
    v1.push_back(P(a,b));
  }
  for(int i=0;i<n;i++){
    cin >> a >> b;
    v2.push_back(P(a,b));
  }
  sort(v1.begin(), v1.end());
  sort(v2.begin(), v2.end());
  int cnt=0;
  for(int j=0;j<n;j++){
    int mxi=-1, mx=-1;
    for(int i=0;i<n;i++){
      if(check[i]==0 && v1[i].first<v2[j].first && v1[i].second<v2[j].second && mx<v1[i].second){
        mxi = i;
        mx = v1[i].second;
      }
    }
    if(mxi!=-1){
      check[mxi]=1;
      cnt++;
    }
  }
  cout << cnt << 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<cstring>
#include<vector>
#include<algorithm>

#define P pair<int, int>

using namespace std;

int main(){
  int n, a, b, check[109];
  memset(check, 0 , sizeof(check));
  cin >> n;
  vector<P> v1, v2;
  for(int i=0;i<n;i++){
    cin >> a >> b;
    v1.push_back(P(a,b));
  }
  for(int i=0;i<n;i++){
    cin >> a >> b;
    v2.push_back(P(a,b));
  }
  sort(v1.begin(), v1.end());
  sort(v2.begin(), v2.end());
  int cnt=0;
  for(int j=0;j<n;j++){
    int mxi=-1, mx=-1;
    for(int i=0;i<n;i++){
      if(check[i]==0 && v1[i].first<v2[j].first && v1[i].second<v2[j].second && mx<v1[i].second){
        mxi = i;
        mx = v1[i].second;
      }
    }
    if(mxi!=-1){
      check[mxi]=1;
      cnt++;
    }
  }
  cout << cnt << endl;
}
```