#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
#define all(x) (x).begin(),(x).end()
const int mod=1000000007;

bool ssort(pair<int,int> a,pair<int,int> b){
    return a.second>b.second;
}

int main(){
    
    int N;cin>>N;
    vector<pair<int,int>> S(N),T(N);
    for(int i=0;i<2*N;i++){
        if(i<N) cin>>S[i].first>>S[i].second;
        else cin>>T[i-N].first>>T[i-N].second;
    }
    sort(all(S),ssort);
    sort(all(T));
    int cnt=0;
    for(int i=0;i<N;i++){
        for(int j=0;j<N;j++){
            if(S[i].first<T[j].first&&S[i].second<T[j].second){
                cnt++;
                T[j]=make_pair(-1,-1);
                break;
            }
        }
    }
    cout<<cnt<<endl;
}

### Prompt

Your challenge is to write 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 <bits/stdc++.h>
using namespace std;

typedef long long ll;
#define all(x) (x).begin(),(x).end()
const int mod=1000000007;

bool ssort(pair<int,int> a,pair<int,int> b){
    return a.second>b.second;
}

int main(){
    
    int N;cin>>N;
    vector<pair<int,int>> S(N),T(N);
    for(int i=0;i<2*N;i++){
        if(i<N) cin>>S[i].first>>S[i].second;
        else cin>>T[i-N].first>>T[i-N].second;
    }
    sort(all(S),ssort);
    sort(all(T));
    int cnt=0;
    for(int i=0;i<N;i++){
        for(int j=0;j<N;j++){
            if(S[i].first<T[j].first&&S[i].second<T[j].second){
                cnt++;
                T[j]=make_pair(-1,-1);
                break;
            }
        }
    }
    cout<<cnt<<endl;
}

```