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

from collections import defaultdict
d = defaultdict(list)
for _ in range(N):
    a,b = map(int,input().split())
    d[b].append(a)
K = int(input())
c = list(map(int,input().split()))

u = []
for b in d:
    l = d[b]
    l.sort()
    l[-1] += X
    for i in l:
        u.append(i)
u.sort(reverse = True)
for i in range(len(u) - 1):
    u[i + 1] += u[i]
ans = 0
for i in c:
    if i == 0:continue
    ans += u[i-1]
print(ans)