Sunscreen

To avoid an unsightly burn while tanning at the beach, each of the $C$ cows ($1 \le C \le 2500$) must cover her hide with sunscreen. Cow $i$ works only with a range of SPF ratings, given by a minimum $\text{minSPF}_i$ and a maximum $\text{maxSPF}_i$ ($1 \le \text{minSPF}_i \le 1000$, $\text{minSPF}_i \le \text{maxSPF}_i \le 1000$). If the SPF rating is too low the cow gets sunburned; if it is too high the cow does not tan at all.

The cows share a picnic basket holding $L$ bottles of sunscreen lotion ($1 \le L \le 2500$). Bottle $i$ has an SPF rating $\text{SPF}_i$ ($1 \le \text{SPF}_i \le 1000$) and can be applied to at most $\text{cover}_i$ cows. Each cow may use lotion from only one bottle.

Cow $i$ is protected by bottle $j$ if and only if $\text{minSPF}_i \le \text{SPF}_j \le \text{maxSPF}_i$. What is the maximum number of cows that can protect themselves while tanning with the available lotion?

• Line 1: Two space-separated integers, $C$ and $L$.
• Lines 2 to $C+1$: Line $i+1$ describes cow $i$ with two integers, $\text{minSPF}_i$ and $\text{maxSPF}_i$.
• Lines $C+2$ to $C+L+1$: Each line describes one lotion bottle with two space-separated integers, $\text{SPF}_i$ and $\text{cover}_i$.

Print a single integer: the maximum number of cows that can be protected while tanning.