import collections
import numpy as np
def main():
  N,M,X=map(int,input().split( ))
  A=list(range(N))
  B=list(range(N))
  for num in range(N):
    A[num],B[num]=map(int,input().split( ))
  K=int(input())
  s=0
  t=0
  D=np.zeros((N,N))
  C=list(map(int,input().split()))
  for i in range(M):
    for j in range(N):
     if B[j]==i + 1:
       D[i][s]=A[j]
       s=s + 1
    s=0
  for i in range(M): 
   for j in range(N):
     if A[j]==max(D[i]) and B[j]==i + 1:
       A[j]=A[j] + X
       break
  E=sorted(A,reverse=True)
  for i in range(K):
    for j in range(C[i]):
     t=t + E[j]
  print(t)
if __name__ == '__main__':
  main()