import sys
input = sys.stdin.readline
from collections import *

N, M, X = map(int, input().split())
d = defaultdict(list)

for _ in range(N):
    A, B = map(int, input().split())
    d[B].append(A)

l = []

for k in d:
    d[k].sort()
    d[k][-1] += X
    l += d[k]

l.sort(reverse=True)
acc = [0]

for li in l:
    acc.append(acc[-1]+li)

K = int(input())
C = list(map(int, input().split()))
ans = 0

for Ci in C:
    ans += acc[Ci]

print(ans)