#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
#define FOR(i,a,b) for(int i = (a) , _b = (b); i <= _b; ++i)
#define MASK(x) ((LL)(1)<<(x))
#define BIT(mask , x) (((mask)>>x)&(1))
#define sz(x) (int)(x).size()
template<class X,class Y>
bool maximize(X &x , Y y){
if (x < y) return x = y , true; else return false;
}
template<class X,class Y>
bool minimize(X &x , Y y){
if (x > y) return x = y , true; else return false;
}
template<class T>
void compress(vector<T>&data){
sort(data.begin() , data.end());
data.resize(unique(data.begin() , data.end()) - data.begin());
}
template<class X,class Y>
int Find(vector<X>&data,Y y){
return upper_bound(data.begin() , data.end() , y) - data.begin();
}
const int N = (int) 200000;
const int MAXLOG = (int)19;
int a[N + 2] , b[N + 2] , t[N + 2];
int rmq[N*3 + 2][MAXLOG + 2];
int LOG[N*3+2];
int n , k;
vector<int>v;
int limit_size = 0;
struct Node{
int pos;
int x , y;
int index;
bool operator < (const Node&other) const{
return pos > other.pos;
}
};
int Get_max_index(int l , int r){
int x = LOG[r - l + 1];
return max(rmq[l][x] , rmq[r - MASK(x) + 1][x]);
}
int bit[N * 3 + 2];
void upd(int pos , int val){
for(;pos; pos -= pos&-pos) bit[pos] += val;
return;
}
int Get(int pos){
int sum = 0;
for(;pos <= limit_size; pos += pos&-pos) sum+=bit[pos];
return sum;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0) ; cout.tie(0) ;
#define name "main"
if (fopen(name".inp","r")){
freopen(name".inp","r",stdin);
freopen(name".out","w",stdout);
}
cin >> n >> k;
for(int i = 1; i <= n; ++i) {
cin >> a[i] >> b[i];
v.push_back(a[i]) , v.push_back(b[i]);
}
for(int i = 1; i <= k; ++i){
cin >> t[i];
v.push_back(t[i]);
}
compress(v);
limit_size = sz(v);
// for(auto& x : v) cout << x << ' '; cout << '\n';
for(int i = 1; i <= k; ++i) {
t[i] = Find(v , t[i]);
// cout << t[i] << '\n';
maximize(rmq[t[i]][0] , i);
}
FOR(i,2,limit_size) LOG[i] = LOG[i/2] + 1;
FOR(j,1,MAXLOG){
for(int i = 1; i <= limit_size - MASK(j) + 1; ++i){
rmq[i][j] = max(rmq[i][j - 1] , rmq[i + MASK(j - 1)][j - 1]);
}
}
vector<Node>events;
for(int i = 1; i <= n; ++i){
a[i] = Find(v , a[i]) , b[i] = Find(v , b[i]);
int mx = max(a[i] , b[i]) , mn = min(a[i] , b[i]);
int last_index_change = Get_max_index(mn , mx - 1);
if (last_index_change == 0) events.push_back({last_index_change , a[i] , b[i] , i});
else events.push_back({last_index_change , mx , mn , i});
}
sort(events.begin() , events.end());
int i = k;
LL ans = 0;
for(auto& id : events){
while (i > id.pos) upd(t[i--] , 1);
int numsteps = Get(id.x);
int tt ;
if (numsteps % 2==0) tt = v[id.x - 1] ; else tt = v[id.y - 1];
// cout << id.index << ' ' << id.pos << ' ' << tt << '\n';
ans += tt;
}
cout << ans;
}
