from sys import stdin,setrecursionlimit#,set_int_max_str_digits
#import pypyjit
#pypyjit.set_param('max_unroll_recursion=-1')
setrecursionlimit(20000000) # これこどふぉだと無理
#set_int_max_str_digits(200010)
mod = 998244353 
ii = lambda :int(stdin.readline())
mi = lambda :map(int,stdin.readline().split())
li = lambda :list(mi())
gmi = lambda :map(lambda x: int(x) - 1, stdin.readline().split())
gi = lambda :list(map(lambda x: 0 if x == "." else 1,input())) # グリッド入力受け取り
py = lambda :print("Yes")
pn = lambda :print("No")
pf = lambda :print("First") 
ps = lambda :print("Second")
vec = [(1,0),(-1,0),(0,-1),(0,1)]
vec1 = [(1,0),(1,1),(0,1),(-1,1),(-1,0),(-1,-1),(0,-1),(1,-1)] #8方向
inf = 2*10**18

from collections import defaultdict 

n,m,x = mi() 

data = defaultdict(list) 

for _ in range(n):
    a,b = mi() 
    data[b].append(a) 

prob = [] 
for i in data:
    data[i].sort() 
    data[i][-1] += x
    for v in data[i]:
        prob.append(v)

prob.sort(reverse=True)
k = ii() 
a = li() 

k = max(a) + 1 

c = [0]*k 
for i in a:
    c[i-1] += 1 


tmp = 0 
ans = 0 

for i in range(k-1):
    tmp += prob[i] 
    ans += tmp*c[i] 

print(ans)