import sys
input = sys.stdin.readline

N,M,p=map(int,input().split())
P=[tuple(map(int,input().split())) for i in range(N)]
K=int(input())
C=list(map(int,input().split()))

X=[[] for i in range(10**7+1)]

for a,b in P:
    X[b].append(a)

XX=[]

for i in range(10**7+1):
    X[i].sort()
    if len(X[i])>0:
        X[i][-1]+=p
        XX+=X[i]

XX.sort(reverse=True)

S=[0]
for xx in XX:
    S.append(S[-1]+xx)

ANS=0

for c in C:
    ANS+=S[c]

print(ANS)