n,m,x = map(int,input().split())
L = [[] for _ in range(m+1)]
for _ in range(n):
    a,b = map(int,input().split())
    L[b].append(a)
Z = []
for l in L:
    if not l:
        continue
    l.sort()
    l[-1] += x
    for z in l:
        Z.append(z)
Z.sort(reverse=True)
D = [0]*(n+1)
for i,z in enumerate(Z):
    D[i+1] = D[i]+z
k = int(input())
C = tuple(map(int,input().split()))
ans = 0
for c in C:
    ans += D[c]
print(ans)