#include<iostream>
#include<algorithm>
#include<vector>
typedef long long int ll;
#define rep(i,a,b) for(int i=(a);i<(b);i++)
using namespace std;

int N;
pair<int, int> a[101];
pair<int, int> b[101];
int ans = 0;

int main() {
	cin >> N;
	rep(i, 0, N)cin >> a[i].second >> a[i].first;
	rep(i, 0, N)cin >> b[i].first >> b[i].second;

	sort(a, a + N);
	sort(b, b + N);

	vector<int> h;
	rep(i, 0, N)h.push_back(0);

	rep(i, 0, N) {
		int max = 0;
		int hantei = -1;
		rep(j, 0, N) {
			if (b[i].first > a[j].second && b[i].second > a[j].first && h[j] == 0) {
				if (max <= a[j].first) {
					max = a[j].first;
					hantei = j;
				}
			}
		}
		if (hantei >= 0) {
			h[hantei] = 1;
			ans++;
		}
	}

	cout << ans << endl;

	return 0;
}
### Prompt

Please provide a cpp coded solution 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<iostream>
#include<algorithm>
#include<vector>
typedef long long int ll;
#define rep(i,a,b) for(int i=(a);i<(b);i++)
using namespace std;

int N;
pair<int, int> a[101];
pair<int, int> b[101];
int ans = 0;

int main() {
	cin >> N;
	rep(i, 0, N)cin >> a[i].second >> a[i].first;
	rep(i, 0, N)cin >> b[i].first >> b[i].second;

	sort(a, a + N);
	sort(b, b + N);

	vector<int> h;
	rep(i, 0, N)h.push_back(0);

	rep(i, 0, N) {
		int max = 0;
		int hantei = -1;
		rep(j, 0, N) {
			if (b[i].first > a[j].second && b[i].second > a[j].first && h[j] == 0) {
				if (max <= a[j].first) {
					max = a[j].first;
					hantei = j;
				}
			}
		}
		if (hantei >= 0) {
			h[hantei] = 1;
			ans++;
		}
	}

	cout << ans << endl;

	return 0;
}
```