N,M,X = map(int, input().split(" "))

questions = []
for i in range(N):
    questions.append(list(map(int, input().split(" "))))

K = int(input())
num_answers = list(map(int, input().split(" ")))


def calc_confident(question_list, num_answers, X):
    sum = 0
    for num in num_answers:
        janru = set()
        for i in range(num):
            janru.add(question_list[i][1])
            sum += question_list[i][0]
        sum += len(janru)*X
    return sum


def get_max(questions, now_list, N, X):
    sorted_list = sorted(questions, key= lambda x:-x[0])
    if not now_list:
        return sorted_list[0]

    j_set = set([j[1] for j in now_list])
    n_j = len(j_set)
    if n_j == N:
        return sorted_list[0]

    max_q = sorted_list[0]
    other_j_list = [s for s in sorted_list if s[1] not in j_set]
    if not other_j_list:
        return max_q
    max_q_j = other_j_list[0]

    if max_q == max_q_j:
        return max_q

    dif = max_q[0] - max_q_j[0]
    if dif > X:
        return max_q
    else:
        return max_q_j

now_list = []
for i in range(len(questions)):
    max_q =get_max(questions, now_list, N,X)

    now_list.append(max_q)
    questions.remove(max_q)



val = calc_confident(now_list, num_answers, X)
print(val)