#import sys
# input = sys.stdin.readline
def mp():return map(int,input().split())
def lmp():return list(map(int,input().split()))
def mps(A):return [tuple(map(int, input().split())) for _ in range(A)]
import math
import bisect
import heapq
from copy import deepcopy as dc
from itertools import accumulate
from collections import Counter, defaultdict, deque
def ceil(U,V):return (U+V-1)//V
def modf1(N,MOD):return (N-1)%MOD+1
inf = int(1e20)
mod = int(1e9)+7

n,m,x = mp()
score = [[] for i in range(m)]
for i in range(n):
    a,b = mp()
    b -= 1
    score[b].append(a)
for i in range(m):
    score[i].sort(reverse=True)
for i in range(m):
    if score[i]:score[i][0] += x
k = int(input())
c = lmp()
hq = []
heapq.heapify(hq)
for i in range(m):
    for j in score[i]:
        heapq.heappush(hq,-j)
ans = []
for i in range(n):
    u = heapq.heappop(hq)
    ans.append(-u)
ans = [0]+list(accumulate(ans))
cnt = 0
for i in c:
    cnt += ans[i]
print(cnt)