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