N,M,X = map(int,input().split())
d = {x:[] for x in range(1,M+1)}


for i in range(N):
    A,B = map(int,input().split())
    d[B].append(A)

l = []
for k,v in d.items():
    tmp = sorted(v)
    if tmp:tmp[-1]+=X
    l+=tmp

l.sort(reverse=True)
com = [0]
for i in range(len(l)):
    com.append(com[i]+l[i])

K = int(input())
C = list(map(int,input().split()))

ans = 0
for i in C:
    ans+=com[i]
print(ans)