N, M, X = map(int, input().split())
problems = [list(map(int, input().split())) for _ in range(N)]
problems.sort(reverse=True)
used = [False] * (M + 1)
for i in range(N):
    if used[problems[i][1]]:
        continue
    problems[i][0] += X
    used[problems[i][1]] = True
problems.sort(reverse=True)

score = [0]
for p in problems:
    score.append(score[-1] + p[0])

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

ans = 0
for c in C:
    ans += score[c]

print(ans)