n, m, x = map(int, input().split())

problems = {}
for _ in range(n):
  a, b = map(int, input().split())
  if problems.get(b, None) is None:
    problems[b] = []

  problems[b].append(a)

k = int(input())
c = list(map(int, input().split()))

q = []
for _, vs in problems.items():
  vs.sort()
  q.append(vs.pop() + x)
  for v in vs:
    q.append(v)

q.sort(reverse=True)

score = [0 for _ in range(n + 1)]
for i in range(n):
  score[i + 1] = score[i] + q[i]

ans = 0
for i in range(k):
  ans += score[c[i]]

print(ans)