from collections import defaultdict
import sys
readline=sys.stdin.readline

class Cumsum:
    def __init__(self,lst,mod=0):
        self.N=len(lst)
        self.mod=mod
        self.cumsum=[0]*(self.N+1)
        self.cumsum[0]=0
        for i in range(1,self.N+1):
            self.cumsum[i]=self.cumsum[i-1]+lst[i-1]
            if self.mod:
                self.cumsum[i]%=self.mod

    def __getitem__(self,i):
        if type(i)==int:
            if 0<=i<self.N:
                a,b=i,i+1
            elif -self.N<=i<0:
                a,b=i+self.N,i+self.N+1
            else:
                raise IndexError('list index out of range')
        else:
            a,b=i.start,i.stop
            if a==None or a<-self.N:
                a=0
            elif self.N<=a:
                a=self.N
            elif a<0:
                a+=self.N
            if b==None or self.N<=b:
                b=self.N
            elif b<-self.N:
                b=0
            elif b<0:
                b+=self.N
        s=self.cumsum[b]-self.cumsum[a]
        if self.mod:
            s%=self.mod
        return s

    def __setitem__(self,i,x):
        if -self.N<=i<0:
            i+=self.N
        elif not 0<=i<self.N:
            raise IndexError('list index out of range')
        self.cumsum[i+1]=self.cumsum[i]+x
        if self.mod:
            self.cumsum[i+1]%=self.mod

    def __str__(self):
        lst=[self.cumsum[i+1]-self.cumsum[i] for i in range(self.N)]
        if self.mod:
            for i in range(self.N):
                lst[i]%=self.mod
        return "["+", ".join(map(str,lst))+"]"

N,M,X=map(int,readline().split())
dct=defaultdict(list)
for i in range(N):
    A,B=map(int,readline().split())
    dct[B].append(A)
lst=[]
for B in dct.keys():
    dct[B].sort()
    dct[B][-1]+=X
    lst+=dct[B]
K=int(readline())
lst.sort(reverse=True)
lst=Cumsum(lst)
ans=0
for c in map(int,readline().split()):
    ans+=lst[:c]
print(ans)