import java.util.*;

class Jewel implements Comparable<Jewel> {
    int weight, cost;

    public Jewel(int weight, int cost) {
        this.weight = weight;
        this.cost = cost;
    }

    @Override
    public int compareTo(Jewel o) {
        return Integer.compare(o.cost, this.cost);
    }
}

public class _1202 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int K = sc.nextInt();

        ArrayList<Jewel> jewels = new ArrayList<>();
        for(int i=0; i<N; i++) jewels.add(new Jewel(sc.nextInt(), sc.nextInt()));
        Collections.sort(jewels, (a,b) -> Integer.compare(a.weight, b.weight));

        int[] bags = new int[K];
        for(int i=0; i<K; i++) bags[i] = sc.nextInt();
        Arrays.sort(bags);

        sc.close();

        long ans = 0;
        int idx = 0;
        PriorityQueue<Jewel> pq = new PriorityQueue<>();

        for (int m : bags) {
            while(idx < N && m >= jewels.get(idx).weight) pq.add(jewels.get(idx++));
            if(!pq.isEmpty()) ans += pq.poll().cost;
        }

        System.out.println(ans);
    }
}