#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
const int N=(int)2e5;
const int MAXLOG=16;
vector<int>nen;
int a[N+2],b[N+2],t[N+2];
int n,k;
int Find(vector<int>&x,int val){
return upper_bound(x.begin(),x.end(),val)-x.begin();
}
int rmq[N*3+2][MAXLOG+2],LOG[N+2];
struct Node{
int pos,x,y;
bool operator < (const Node&other) const{
return pos>other.pos;
}
};
int Getmax(int l,int r){
if (l>r) return 0;
int x=LOG[r-l+1];
return max(rmq[l][x],rmq[r-(1<<x)+1][x]);
}
vector<Node>event;
int lim;
int bit[3*N+2];
void add(int pos,int x){
for(;pos<=lim;pos+=pos&-pos) bit[pos]+=x;
return;
}
int Get(int pos){
int sum=0;
for(;pos;pos-=pos&-pos) sum+=bit[pos];
return sum;
}
int sum_range(int l,int r){
return Get(r)-Get(l-1);
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0) ; cout.tie(0);
cin>>n>>k;
lim=3*N;
for(int i=1;i<=n;++i){
cin>>a[i]>>b[i];
nen.push_back(a[i]),
nen.push_back(b[i]);
}
for(int i=1;i<=k;++i){
cin>>t[i];
nen.push_back(t[i]);
}
sort(nen.begin(),nen.end());
nen.resize(unique(nen.begin(),nen.end())-nen.begin());
for(int i=1;i<=n;++i){
a[i]=Find(nen,a[i]),
b[i]=Find(nen,b[i]);
}
for(int i=1;i<=k;++i) {
t[i]=Find(nen,t[i]);
rmq[t[i]][0]=max(rmq[t[i]][0],i);
}
for(int i=2;i<=n;++i) LOG[i]=LOG[i/2]+1;
for(int j=1;j<=MAXLOG;++j){
for(int i=1;i+(1<<j)-1<=lim;++i){
rmq[i][j]=max(rmq[i][j-1],rmq[i+(1<<(j-1))][j-1]);
}
}
for(int i=1;i<=n;++i) {
int mx=max(a[i],b[i]),mn=min(a[i],b[i]);
int lastbit=Getmax(mn,mx-1);
if (lastbit==0) event.push_back({lastbit,a[i],b[i]});
else event.push_back({lastbit,mx,mn});
}
sort(event.begin(),event.end());
int idx=k;
LL ans=0;
for(auto&x:event) {
while (idx>=1 && idx>=x.pos){
add(t[idx--],1);
}
int numflip=sum_range(x.x,lim);
// cout<<x.pos<<' '<<nen[x.x-1]<<' '<<nen[x.y-1]<<' '<<numflip<<'\n';
ans+=(numflip%2==0?nen[x.x-1]:nen[x.y-1]);
}
cout<<ans;
}
