import sys, math
sys.setrecursionlimit(10**8)
sys.set_int_max_str_digits(0)
INF = 1e18
MOD = 998244353
from bisect import bisect_left, bisect_right
from collections import deque, defaultdict, Counter
from itertools import product, combinations, permutations, groupby, accumulate
from heapq import heapify, heappop, heappush
input = sys.stdin.readline
def I():   return input().rstrip()
def II():  return int(input().rstrip())
def IS():  return input().rstrip().split()
def MII(): return map(int, input().rstrip().split())
def LI():  return list(input().rstrip())
def TII(): return tuple(map(int, input().rstrip().split()))
def LII(): return list(map(int, input().rstrip().split()))
def LSI(): return list(map(str, input().rstrip().split()))
def GMI(): return list(map(lambda x: int(x) - 1, input().rstrip().split()))
def kiriage(a, b): return (a+b-1)//b

N, M, X = MII()

genre = [list() for _ in range(M)]
for i in range(N):
    a, b = MII()
    # a ... quality, b ... genre
    b -= 1
    genre[b].append(a)

K = II()
C = LII()
# 各問題を解く人数
cnt = [0]*(N + 2)
for c in C:
    if c != 0:
        cnt[1] += 1
        cnt[c + 1] -= 1

for i in range(1, N + 1):
    cnt[i + 1] += cnt[i]

que = []
# 問題を解く順を決める
# 各ジャンルの最高問題をqueに入れる
for i in range(M):
    if genre[i]:
        genre[i].sort()
        target = genre[i].pop() + X
        heappush(que, (-target, i))

# 一問目から順に割り当てる
ans = 0
for i in range(1, N + 1):
    mondai, genreid = heappop(que)
    mondai *= -1
    # cnt[i] 人解く
    ans += mondai * cnt[i]
    
    # そのジャンル、後続がいれば補充する
    if genre[genreid]:
        target = genre[genreid].pop()
        heappush(que, (-target, genreid))

print(ans)