#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define endl '\n'
#define FF first
#define SS second
#define all(a) a.begin(), a.end()
#define mod (ll)(1000000007)
const int pr=20, s_p=1<<pr, e_p=(1<<(pr+1))-1;
int n, k;
vector<int>A, B, T, S_mx, S_sum;
map<int, int>mp, inv;
void pre(){
A.clear(), B.clear(), T.clear(), mp.clear(), inv.clear(), S_mx.clear(), S_sum.clear();
A.resize(n+1), B.resize(n+1), T.resize(k+1), S_mx.resize(1<<(pr+1), -1), S_sum.resize(1<<(pr+1));
}
void update_sum(int ind, int delta){
S_sum[ind]+=delta;
while(ind/=2)
S_sum[ind]+=delta;
}
void update_mx(int ind, int new_){
S_mx[ind]=max(S_mx[ind], new_);
while(ind/=2)
S_mx[ind]=max(S_mx[ind], new_);
}
int get_sum(int id, int u, int v, int l, int r){
if(l>v || r<u)
return 0;
if(l>=u && r<=v)
return S_sum[id];
int md=(l+r)/2;
int fir=get_sum(id*2, u, v, l, md);
int sec=get_sum(id*2+1, u, v, md+1, r);
return fir+sec;
}
int get_mx(int id, int u, int v, int l, int r){
if(l>v || r<u)
return -1;
if(l>=u && r<=v)
return S_mx[id];
int md=(l+r)/2;
int fir=get_mx(id*2, u, v, l, md);
int sec=get_mx(id*2+1, u, v, md+1, r);
return max(fir, sec);
}
void comp(){
vector<int>S=T;
for(int i=1;i<=n;i++){
S.push_back(A[i]);
S.push_back(B[i]);
}
sort(all(S));
int cnt=1;
for(int i=0;i<S.size();i++){
if(!i || S[i]!=S[i-1]){
mp[S[i]]=cnt, inv[cnt]=S[i], cnt++;
}
}
for(int i=1;i<=n;i++){
A[i]=mp[A[i]], B[i]=mp[B[i]];
}
for(int j=0;j<k;j++){
T[j]=mp[T[j]];
}
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);
cin>>n>>k;
pre();
for(int i=1;i<=n;i++){
cin>>A[i]>>B[i];
}
for(int j=0;j<k;j++){
cin>>T[j];
}
comp();
for(int j=0;j<k;j++){
update_mx(T[j]+s_p, j);
}
vector<vector<int>>Q(k);
ll ans=0;
for(int i=1;i<=n;i++){
int mn=min(A[i], B[i]), mx=max(A[i], B[i]);
if(mn==mx){
ans+=inv[mn];
continue;
}
int mx_ind=get_mx(1, mn+s_p, mx-1+s_p, s_p, e_p);
Q[(mx_ind>=0?mx_ind:0)].push_back((mx_ind>=0?i:-i));
}
for(int j=k-1;j>=0;j--){
update_sum(T[j]+s_p, 1);
for(int f=0;f<Q[j].size();f++){
int mn=min(A[abs(Q[j][f])], B[abs(Q[j][f])]), mx=max(A[abs(Q[j][f])], B[abs(Q[j][f])]);
int sum=get_sum(1, mx+s_p, e_p, s_p, e_p);
if(Q[j][f]<0){
if(sum&1)
ans+=inv[B[abs(Q[j][f])]];
else
ans+=inv[A[abs(Q[j][f])]];
continue;
}
if(sum&1)
ans+=inv[mn];
else
ans+=inv[mx];
}
}
cout<<ans;
}
