import collections
N,M,X = map(int,input().split())
lsAB = collections.defaultdict(lambda :[])
for i in range(N):
    a,b = map(int,input().split())
    lsAB[b].append(a)
K = int(input())
lsC = list(map(int,input().split()))
for key in lsAB.keys():
    lsAB[key].sort(reverse=True)
for key in lsAB.keys():
    lsAB[key][0] += X
lsAll = []
for key in lsAB.keys():
    for i in lsAB[key]:
        lsAll.append(i)
lsAll.sort(reverse=True)
lssum = [0]
for i in range(N):
    lssum.append(lssum[-1]+lsAll[i])
ans = 0
for i in range(K):
    ans += lssum[lsC[i]]

print(ans)