#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
typedef tuple<int,int,int> ti;
typedef vector<ll> li;
typedef vector<li> lii;
#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define LSOne(s) ((s)&(-s))
#define all(x) x.begin(),x.end()
ll INF=1000000000000000010;
int inf=1e9+10;
ll M=1e9+7;
int n,q,m,k;
unordered_map<int,int> mp;
vi a,b,arr,c,ft;
vector<ti> A;
vii mx;
void update(int x){
x++;
while(x<=m){
ft[x]++;
x+=LSOne(x);
}
}
int query(int x){
x++;
int ans=0;
while(x){
ans+=ft[x];
x-=LSOne(x);
}
return ans;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin>>n>>q;
a.resize(n);b.resize(n);A.resize(n);
REP(i,0,n){
cin>>a[i]>>b[i];
arr.PB(a[i]);
arr.PB(b[i]);
}
sort(all(arr));
arr.erase(unique(all(arr)),arr.end());
m=arr.size();
k=log2(m)+1;
REP(i,0,m)mp[arr[i]]=i;
mx.resize(m,vi(k,-1));
c.resize(q,-1);
REP(i,0,q){
int x;cin>>x;
auto it=upper_bound(all(arr),x);
if(it==arr.begin())continue;
it--;
int ps=it-arr.begin();
c[i]=ps;
mx[ps][0]=i;
}
REP(i,0,n)a[i]=mp[a[i]];
REP(i,0,n)b[i]=mp[b[i]];
REP(i,0,n)A[i]={max(a[i],b[i]),min(a[i],b[i]),i};
sort(all(A));reverse(all(A));
ft.resize(m+1,0);
REP(j,1,k)REP(i,0,m)if(i+(1<<(j-1))<m)mx[i][j]=max(mx[i][j-1],mx[i+(1<<(j-1))][j-1]);
ll ans=0;
priority_queue<pi> pq;
REP(i,0,q)pq.push({c[i],i});
REP(i,0,n){
auto [x,y,z]=A[i];
swap(x,y);
int t=y-1;
int pos=-1;
if(y>x){
int dif=0;
if(t!=x)dif=log2(t-x);
pos=max(mx[x][dif],mx[t-(1<<dif)+1][dif]);
}
while(!pq.empty()&&pq.top().F>=y){
update(pq.top().S);
pq.pop();
}
int cnt=query(m-1)-query(pos);
if(pos==-1){
if(cnt%2==0)ans+=(ll)arr[a[z]];
else ans+=(ll)arr[b[z]];
}
else{
if(cnt%2==0)ans+=(ll)arr[y];
else ans+=(ll)arr[x];
}
}
cout<<ans;
}
