from collections import deque
n,m,x = map(int,input().split())
lis = []
for _ in range(n):
  ab = list(map(int,input().split()))
  lis.append(ab)

u = int(input())
t = list(map(int,input().split()))

t_max = max(t)
dp = [-10**18] * (t_max+1)
dp[0] = 0
already_ind = set()
subject = set()
for i in range(1,t_max+1):
    for j in range(n):
        if(j not in already_ind):
            if(lis[j][1] not in subject):
                if(dp[i] < dp[i-1] + lis[j][0] + x):
                    dp[i] = dp[i-1] + lis[j][0] + x
                    max_ind = j
            else:
                if(dp[i] < dp[i-1] + lis[j][0]):
                    dp[i] = dp[i-1] + lis[j][0]
                    max_ind = j
  
    already_ind.add(max_ind)         
    subject.add(lis[max_ind][1])

ans = 0
for i in range(u):
  ans += dp[t[i]]
print(ans)