#include <bits/stdc++.h>
#define P pair<int,int>
using namespace std;
const int INF = 1e9 + 7, MOD = 1e9 + 7;
const long long LINF = 1e18;
const int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
int main() {
	int n;
	cin >> n;
	vector<pair<int, int> > Red(n), Blue(n);
	for (int i = 0; i < n; i++) {
		cin >> Red[i].second >> Red[i].first;
	}
	for (int i = 0; i < n; i++) {
		cin >> Blue[i].first >> Blue[i].second;
	}
	sort(Red.begin(), Red.end(), greater<pair<int, int> >());
	sort(Blue.begin(), Blue.end());
	int ans = 0;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			if (Red[j].second < Blue[i].first && Red[j].first < Blue[i].second) {
				ans++;
				Red[j].first = INF, Red[j].second = INF;
				break;
			}
		}
	}
	cout << ans << endl;
	return 0;
}
### Prompt

Your task is to create 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>
#define P pair<int,int>
using namespace std;
const int INF = 1e9 + 7, MOD = 1e9 + 7;
const long long LINF = 1e18;
const int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
int main() {
	int n;
	cin >> n;
	vector<pair<int, int> > Red(n), Blue(n);
	for (int i = 0; i < n; i++) {
		cin >> Red[i].second >> Red[i].first;
	}
	for (int i = 0; i < n; i++) {
		cin >> Blue[i].first >> Blue[i].second;
	}
	sort(Red.begin(), Red.end(), greater<pair<int, int> >());
	sort(Blue.begin(), Blue.end());
	int ans = 0;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			if (Red[j].second < Blue[i].first && Red[j].first < Blue[i].second) {
				ans++;
				Red[j].first = INF, Red[j].second = INF;
				break;
			}
		}
	}
	cout << ans << endl;
	return 0;
}
```