n,m,x=map(int,input().split())
ns=[list(map(int,input().split())) for i in range(n)]
k=int(input())
c=list(map(int,input().split()))
ns.sort(reverse=True)
now=-1
s=set()
for i in range(n):
    if ns[i][1] not in s:
        ns[i][0]+=x
        s.add(ns[i][1])
ns.sort(reverse=True)
for i in range(n-1):
    ns[i+1][0]+=ns[i][0]
ans=0    
for i in range(k):
    if c[i] == 0: continue
    ans+= ns[c[i]-1][0]
print(ans)