import sys

# sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# inf = (1 << 31)-1
md = 10**9+7
# md = 998244353

from collections import defaultdict

n, m, x = LI()
aa = defaultdict(list)
for _ in range(n):
    a, b = LI()
    aa[b].append(a)
k = II()
cc = LI()

sat = []
for b in aa:
    aa[b].sort()
    sat += aa[b]
    sat[-1] += x

sat.sort(reverse=True)
cs = [0]
for s in sat: cs.append(cs[-1]+s)

ans = 0
for c in cc: ans += cs[c]

print(ans)