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题目描述

To avoid unsightly burns while tanning, each of the C (1 ≤ C ≤ 2500) cows must cover her hide with sunscreen when they're at the beach. Cow i has a minimum and maximum SPF rating (1 ≤ minSPFi ≤ 1,000; minSPFi ≤ maxSPFi ≤ 1,000) that will work. If the SPF rating is too low, the cow suffers sunburn; if the SPF rating is too high, the cow doesn't tan at all........

The cows have a picnic basket with L (1 ≤ L ≤ 2500) bottles of sunscreen lotion, each bottle i with an SPF rating SPFi (1 ≤ SPFi ≤ 1,000). Lotion bottle i can cover coveri cows with lotion. A cow may lotion from only one bottle.

What is the maximum number of cows that can protect themselves while tanning given the available lotions?

有 $C$ 头奶牛进行日光浴，第 $i$ 头奶牛需要 $minSPF[i]$ 到 $maxSPF[i]$ 单位强度之间的阳光。

每头奶牛在日光浴前必须涂防晒霜，防晒霜有 $L$ 种，涂上第 $i$ 种之后，身体接收到的阳光强度就会稳定为 $SPF[i]$，第 $i$ 种防晒霜有 $cover[i]$ 瓶。

求最多可以满足多少头奶牛进行日光浴。

输入格式

* Line 1: Two space-separated integers: C and L

* Lines 2..C+1: Line i describes cow i's lotion requires with two integers: minSPFi and maxSPFi

* Lines C+2..C+L+1: Line i+C+1 describes a sunscreen lotion bottle i with space-separated integers: SPFi and coveri

第一行输入整数 $C$ 和 $L$。

接下来的 $C$ 行，按次序每行输入一头牛的 $minSPF$ 和 $maxSPF$ 值，即第 $i$ 行输入 $minSPF[i]$ 和 $maxSPF[i]$。

再接下来的 $L$ 行，按次序每行输入一种防晒霜的 $SPF$ 和 $cover$ 值，即第 $i$ 行输入 $SPF[i]$ 和 $cover[i]$。

每行的数据之间用空格隔开。

输出格式

A single line with an integer that is the maximum number of cows that can be protected while tanning

输出一个整数，代表最多可以满足奶牛日光浴的奶牛数目。

3 2
3 10
2 5
1 5
6 2
4 1

2

提示

$1≤C,L≤2500$,$1≤minSPF≤maxSPF≤1000$,$1≤SPF≤1000$。