import sys

input = sys.stdin.readline

N,M,X = map(int,input().split())
Genre = [[] for i in range(M)]
for _ in range(N):
    v,g = map(int,input().split())
    Genre[g-1].append(v)

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

problem = []
for i in range(M):
    if Genre[i]:
        Genre[i].sort(reverse=True)
        Genre[i][0] += X
        problem += Genre[i]

problem.sort(reverse=True)
problem = [0] + problem
for i in range(1,N+1):
    problem[i] += problem[i-1]

ans = 0
for AC in p:
    ans += problem[AC]

print(ans)