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

#define x first
#define y second

int main() {
  int n;
  cin >> n;
  set < pair < int, int > > gay, shit;
  int ans = 0;
  for (int i = 0; i < n; ++i) {
    pair < int, int > gang;
    cin >> gang.first >> gang.second;
    gay.insert(gang);
  }
  for (int i = 0; i < n; ++i) {
    pair < int, int > gang;
    cin >> gang.first >> gang.second;
    shit.insert(gang);
  }
  while (!shit.empty()) {
    auto pr = *shit.begin();
    shit.erase(shit.begin());
    pair < int, int > res = make_pair(-1, -1);
    for (auto gang: gay) {
      if (pr.x > gang.x && pr.y > gang.y)
        res = max(res, make_pair(gang.y, gang.x));
    }
    gay.erase(make_pair(res.y, res.x));
    if (res.first > -1)
      ++ans;
  }
  cout << ans << '\n';
}

### Prompt

Construct a Cpp code solution to the problem outlined:

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;

#define x first
#define y second

int main() {
  int n;
  cin >> n;
  set < pair < int, int > > gay, shit;
  int ans = 0;
  for (int i = 0; i < n; ++i) {
    pair < int, int > gang;
    cin >> gang.first >> gang.second;
    gay.insert(gang);
  }
  for (int i = 0; i < n; ++i) {
    pair < int, int > gang;
    cin >> gang.first >> gang.second;
    shit.insert(gang);
  }
  while (!shit.empty()) {
    auto pr = *shit.begin();
    shit.erase(shit.begin());
    pair < int, int > res = make_pair(-1, -1);
    for (auto gang: gay) {
      if (pr.x > gang.x && pr.y > gang.y)
        res = max(res, make_pair(gang.y, gang.x));
    }
    gay.erase(make_pair(res.y, res.x));
    if (res.first > -1)
      ++ans;
  }
  cout << ans << '\n';
}

```