from collections import Counter
import heapq as hq
N, M, X = map(int, input().split())
A = [list(map(int, input().split())) for _ in range(N)]
K = int(input())
C = list(map(int, input().split()))
D = Counter(C)

INF = 10**9
qual = 0
ct = 0
set1 = [(INF, 0)]
set2 = [(INF, 0)]
for a, b in A:
    hq.heappush(set2, (-a, b))
S = set()
ans = 0
for i in range(1, N+1):
    while set2[0][1] in S:
        a = hq.heappop(set2)
        hq.heappush(set1, a)
    v = -set1[0][0]
    w = -set2[0][0]
    if v <= w+X:
        qual += w
        ct += 1
        S.add(set2[0][1])
        hq.heappop(set2)
    else:
        qual += v
        hq.heappop(set1)
    ans += D[i]*(qual+ct*X)

print(ans)