N, M, X = map(int, input().split())
AB = [[int(i) for i in input().split()] for j in range(N)]

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


problem = {i+1: [] for i in range(M)}
for i in range(N):
    problem[AB[i][1]].append(AB[i][0])
for i in range(M):
    problem[i+1].sort(reverse=True)
    problem[i+1][0] += X
AB.sort(reverse=True, key=lambda x: x[0])

ans_pro = []
for i in range(M):
    ans_pro = ans_pro + problem[i+1]
ans_pro.sort(reverse=True)
for i in range(1, N):
    ans_pro[i] += ans_pro[i-1]
ans = 0
for i in range(K):
    if C[i] > 0:
        ans += ans_pro[C[i]-1]
print(ans)