#include <bits/stdc++.h>
signed main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
int n,k;
std::cin >> n >> k;
std::vector<std::pair<int,int>> mon;
for(int i=0;i<n;i++){
int pos,hel;
std::cin >> pos >> hel;
mon.push_back({pos,hel});
}
std::sort(mon.begin(),mon.end());
std::vector<std::pair<int,int>> mines;
for(int i=0;i<k;i++){
int pos;
std::cin >> pos;
mines.push_back({pos,0});
}
std::sort(mines.begin(),mines.end());
int sum = 0;
for(auto [cPos,cHp]:mon){
std::pair<int,int> tar={cPos,0};
int pos1 = std::min((int)(std::lower_bound(mines.begin(),mines.end(),tar)-mines.begin()),(int)(mines.size()-1));
int pos2 = std::max(0,pos1-1);
int cost1 = std::abs(cPos-mines[pos1].first)+1-mines[pos1].second;
int cost2 = std::abs(cPos-mines[pos2].first)+1-mines[pos2].second;
if(cost1<=cost2&&cost1<=cHp){
mines[pos1].second=1;
sum+=cost1;
}
else if(cost2<=cHp){
mines[pos2].second=1;
sum+=cost2;
}
else{
sum+=cHp;
}
}
std::cout << sum;
}
