import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
sys.setrecursionlimit(10**7)
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

n,m,x = na()
g = [[] for i in range(m)]
for i in range(n):
    a,b = na()
    b-=1
    g[b].append(a)
p = []
for b in range(m):
    g[b] = sorted(g[b])[::-1]
    if len(g[b])>=1:
        p.append(g[b][0]+x)
        for j in range(1,len(g[b])):
            p.append(g[b][j])
p = sorted(p)[::-1]
s = [0]
for i in range(n):
    s.append(p[i]+s[-1])

ans = 0
k = ni()
C = na()
for i in range(k):
    ans += s[C[i]]
print(ans)