#include <bits/stdc++.h>
#define ll long long
using namespace std;
int main(){
ll t,a,b,c,d,e,f,g;
cin>>a>>b;
vector<pair<ll,ll>>vp;
for(int i = 0;i<a;i++){
cin>>c>>d;
vp.push_back({c,d});
}
vector<ll>v(b);
for(int i = 0;i<b;i++){
cin>>v[i];
}
sort(v.begin(),v.end());
sort(vp.begin(),vp.end());
vector<ll>ch(b,0);
ll ans = 0;
for(int i = 0;i<a;i++){
auto it = lower_bound(v.begin(),v.end(),vp[i].first);
auto it2 = it;
if(it == v.begin()){
ll idx = it-v.begin();
if(*it-vp[i].first < vp[i].second){
ch[idx] = 1;
ans += *it-vp[i].first;
}
else{
ans += vp[i].second;
}
}
else if(it == v.end()){
it2--;
ll idx = it2-v.begin();
if(vp[i].first-*it2 < vp[i].second){
ch[idx] = 1;
ans += vp[i].first-*it2;
}
else{
ans += vp[i].second;
}
}
else{
it2--;
ll idx = it-v.begin();
ll idx2 = it2-v.begin();
if(min(*it-vp[i].first,vp[i].first-*it2) < vp[i].second){
if(*it-vp[i].first == vp[i].first-*it2){
if(ch[idx2]){
ch[idx2]++;
ans += vp[i].first-*it2;
}
else{
ch[idx]++;
ans += *it-vp[i].first;
}
}
else if(*it-vp[i].first < vp[i].first-*it2){
ch[idx]++;
ans += *it-vp[i].first;
}
else{
ch[idx2]++;
ans += vp[i].first-*it2;
}
}
else{
ans += vp[i].second;
}
}
}
ll cnt = 0;
for(int i = 0;i<b;i++){
if(ch[i]){
cnt++;
}
}
ans += cnt;
cout<<ans<<endl;
}
//By Rashid_Hashimzade
