#include <map>
#include <queue>
#include <iostream>
#include <stdio.h>
using namespace std;

int main() {
	int m, n;
	int geta, getb, middle;
	long long int result = 0;
	multimap<int, int> cards;
	queue<pair<int, int>> save;

	scanf(" %d %d", &m, &n);
	for (int i = 0; i < m; i++) {
		scanf(" %d %d ", &geta, &getb);
		cards.insert(make_pair(geta, getb));
	}
	for (int i = 0; i < n; i++) {
		scanf(" %d", &middle);
		auto iter = cards.begin();
		
		while (iter->first <= middle) {
			if (iter->second <= middle) {
				save.push(make_pair(iter->first, iter->second));
				
			}
			else {
				cards.insert(make_pair(iter->second, iter->first));
			}
			iter++;
			cards.erase(cards.begin());

			if (iter == cards.end())
				break;
		}
		while (!save.empty()) {
			cards.insert(make_pair(save.front().second, save.front().first));
			save.pop();
		}
	}
	
	for (auto iter = cards.begin(); iter != cards.end(); iter++) {
		result += iter->first;
	}
	
	cout << result;
	cin >> result;

	return 0;
}