/*
██████╗ █████╗ ███████╗██╗ ██╗██╗██████╗
██╔══██╗██╔══██╗██╔════╝██║ ██║██║██╔══██╗
██████╔╝███████║███████╗███████║██║██║ ██║
██╔══██╗██╔══██║╚════██║██╔══██║██║██║ ██║
██║ ██║██║ ██║███████║██║ ██║██║██████╔╝
╚═╝ ╚═╝╚═╝ ╚═╝╚══════╝╚═╝ ╚═╝╚═╝╚═════╝
*/
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ll long long
#define ull unsigned long long
#define ld long double
#define str string
#define ch char
#define db double
#define pb push_back
#define ff first
#define ss second
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define YES cout<<"YES\n";
#define NO cout<<"NO\n";
#define Bob cout<<"Bob\n";
#define Alice cout<<"Alice\n";
#define ordered_set tree<pair<ll, ll>, null_type,less<pair<ll,ll>>,rb_tree_tag,tree_order_statistics_node_update>
const ll MOD=1e9+7;
const ll INF = 10000000000;
void solve(){
ll n,k;
cin>>n>>k;
vector<ll>v(n),h(n);
for(int i = 0;i<n;i++){
cin>>v[i]>>h[i];
}
vector<ll>mina(k);
for(int i = 0;i<k;i++){
cin>>mina[i];
}
ll ans = 0;
bool ok = false;
bool flag = false;
sort(all(mina));
for(int i = 0;i<n;i++){
ll alma = v[i];
ll armud = h[i];
ll mn = LLONG_MAX;
auto it = lower_bound(all(mina),alma);
auto it1 = upper_bound(all(mina),alma);
ll kh=LLONG_MAX;
ll wg=LLONG_MAX;
if(it!=mina.end()){
kh = abs(alma-*it);
}
if(it1!=mina.begin()){
wg = abs(alma-*it1);
}
mn=min({kh,wg,armud});
if(mn==armud)ans+=armud;
else if(mn==kh){
ans+=kh;
ok = true;
}
else{
ans+=wg;
flag = true;
}
}
if(ok){
ans++;
}
if(flag){
ans++;
}
cout<<ans;
}
signed main(){
ll t=1;
//cin>>t;
while(t--){
solve();
}
return 0;
}
