import sys
readline = sys.stdin.readline


N, M, X = map(int, readline().split())
G = [[] for i in range(M)]
A = [0] * N
for i in range(N):
    A[i], B = map(int, readline().split())
    G[B - 1].append((A[i], i))
    
for i in range(M):
    if G[i]:
        G[i].sort(reverse=True)
        A[G[i][0][1]] += X
        
A.sort(reverse=True)
Ac = [0] * (N + 1)
for i in range(N):
    Ac[i + 1] = Ac[i] + A[i]

K = int(readline())
C = list(map(int, readline().split()))
ans = 0
for c in C:
    ans += Ac[c]
print(ans)