#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<pair<ll,ll>>dis(a,{1e9,-1});
for(int i = 0;i<a;i++){
auto it = lower_bound(v.begin(),v.end(),vp[i].first);
if(it != v.end()){
if(*it-vp[i].first < dis[i].first){
dis[i].first = *it-vp[i].first;
ll idx = it-v.begin();
dis[i].second = idx;
}
}
if(it != v.begin()){
it--;
if(vp[i].first-*it < dis[i].first){
dis[i].first = vp[i].first-*it;
ll idx = it-v.begin();
dis[i].second = idx;
}
}
}
ll ans = 0;
vector<ll>ch(b,0);
for(int i = 0;i<a;i++){
if(dis[i].first < vp[i].second){
ans += dis[i].first;
ch[dis[i].second] = 1;
}
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
