n, m, x = map(int, input().split())
P = [[] for _ in range(m)]
for _ in range(n):
    a, b = map(int, input().split())
    b -= 1
    P[b].append(a)
lst = []
for p in P:
    if not p:
        continue
    p.sort(reverse = True)
    p[0] += x
    lst += p
    
lst.sort(reverse = True)
cum = [0]
for l in lst:
    cum.append(cum[-1] + l)
    
k = int(input())
C = list(map(int, input().split()))
print(sum(cum[c] for c in C))