def main():
  import sys
  input=sys.stdin.buffer.readline
  n,m,x=map(int,input().split())
  p=[[] for i in range(m)]
  for i in range(n):
    a,b=map(int,input().split())
    p[b-1].append(a)
  v=[]
  for i in range(m):
    if p[i]:
      p[i].sort(reverse=True)
      p[i][0]+=x
      v+=p[i]
  v.sort(reverse=True)
  u=[0]*(n+1)
  u[0]=int(input())
  C=list(map(int,input().split()))
  for c in C:
    u[c]-=1
  for i in range(n):
    u[i+1]+=u[i]
  ans=0
  for i in range(n):
    ans+=u[i]*v[i]
  print(ans)
main()