- Prepare
- Algorithms
- Graph Theory
- Real Estate Broker

# Real Estate Broker

# Real Estate Broker

You are a real estate broker in ancient Knossos. You have unsold houses, and each house has an area, , and a minimum price, . You also have clients, and each client wants a house with an area greater than and a price less than or equal to .

Each client can buy *at most* one house, and each house can have *at most* one owner. What is the maximum number of houses you can sell?

**Input Format**

The first line contains two space-separated integers describing the respective values of (the number of clients) and (the number of houses).

Each line of the subsequent lines contains two space-separated integers describing the respective values of and for client .

Each line of the subsequent lines contains two space-separated integers describing the respective values of and for house .

**Constraints**

- , where .
- , where .

**Output Format**

Print a single integer denoting the maximum number of houses you can sell.

**Sample Input 0**

```
3 3
5 110
9 500
20 400
10 100
2 200
30 300
```

**Sample Output 0**

```
2
```

**Explanation 0**

Recall that each client is only interested in some house where and . The diagram below depicts which clients will be interested in which houses:

- Client will be interested in house because it has more than units of space and costs less than . Both of the other houses are outside of this client's price range.
- Client will be interested in houses and , as both these houses have more than units of space and cost less than . They will not be interested in the remaining house because it's too small.
- Client will be interested in house because it has more than units of space and costs less than . They will not be interested in the other two houses because they are too small.

All three clients are interested in the same two houses, so you can sell *at most* two houses in the following scenarios:

- Client buys house and client buys house .
- Client buys house and client buys house .
- Client buys house and client buys house .

Thus, we print the maximum number of houses you can sell, , on a new line.