from collections import defaultdict
from itertools import accumulate



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

for k, v in dic.items():
    values = sorted(v, reverse=True)
    data.append(values[0]+X)
    for i in range(1, len(values)):
        data.append(values[i])
data.sort(reverse=True)
data = [0] + list(accumulate(data))
K = int(input())
C = list(map(int, input().split()))

ans = 0
for c in C:
    ans += data[c]
print(ans)