N,M,X = map(int,input().split())
problem = []
for _ in range(N):
    v,g = map(int,input().split())
    problem.append([v,g-1])

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

problem.sort(reverse=True)

used = [False]*M

for i in range(N):
    v,g = problem[i]
    if not used[g]:
        used[g] = True
        problem[i] = v + X
    else:
        problem[i] = v

problem = [0] + problem
for i in range(1,N+1):
    problem[i] += problem[i-1]

ans = 0
for AC in p:
    ans += problem[AC]

print(ans)