import sys
from collections import defaultdict
input = lambda: sys.stdin.readline().rstrip()

#  -----------------------  #

n, m, x = map(int, input().split())
AB = [list(map(int, input().split())) for _ in range(n)]
k = int(input())
C = list(map(int, input().split()))

dic = defaultdict(list)
for a,b in AB:
  dic[b].append(a)
for k in dic.keys():
  dic[k].sort(reverse=True)
  dic[k][0] += x
li = []
for v in dic.values():
  li.extend(v)
li.sort(reverse=True)
acc = [0] * (len(li)+1)
for i in range(len(li)):
  acc[i+1] += acc[i] + li[i]

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