# ジャンルごとに降順ソートして1番にX点加算して全ソート

from collections import defaultdict

N, M, X = map(int, input().split())
dic = defaultdict(list)
for i in range(N):
    a, b = map(int, input().split())
    dic[b].append(a)

all_problems = []
for b in dic:
    dic[b].sort(reverse = True)
    dic[b][0] += X
    all_problems.extend(dic[b])

all_problems.sort(reverse = True)
#print(all_problems)

cumu = [0]
temp = 0
for i in range(N):
    temp += all_problems[i]
    cumu.append(temp)

#print(cumu)

K = int(input())
C = list(map(int, input().split()))
ans = 0
for c in C:
    ans += cumu[c]
print(ans)