from heapq import heappush,heappop

n,m,x = map(int,input().split())
p = [[] for i in range(m)]
for i in range(n):
    a,b = map(int,input().split())
    p[b-1].append(a)

k = int(input())
C = list(map(int,input().split()))
count = [0]*(n+1)
for c in C:
    count[c] += 1

ans = 0
h1 = []
h2 = []
for i in range(m):
    if p[i]:
        p[i].sort()
        heappush(h1,[-p[i].pop(),i])

now = k-count[0]
for i in range(1,n+1):
    if h2 == []:
        ans += x*now
        a,ind = heappop(h1)
        ans += (-a)*now
        for j in p[ind]:
            heappush(h2,-j)
    elif h1 == []:
        a= -heappop(h2)
        ans += a*now

    else:
        if -h1[0][0]+x >= -h2[0]:
            ans += x*now
            a,ind = heappop(h1)
            ans += (-a)*now
            for j in p[ind]:
                heappush(h2,-j)
        else:
            a= -heappop(h2)
            ans += a*now
        
    now -= count[i]
print(ans)