#include <bits/stdc++.h>
#include <fstream>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
#define endl '\n'
#define pb push_back
#define INF 20000000000
#define fi first
#define se second
//#define cin fin
//#define cout fout
using namespace std;
//double const EPS = 1e-14;
typedef long long ll;
//const ll P = 10007;
const ll mod = 1e9 + 7;
//using namespace __gnu_pbds;
//typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set; // find_by_order, order_of_key
const int Max = 2e5 + 5;
ll a[Max], b[Max], pos[Max];
vector<pair<ll,int>> mn, mx;
priority_queue<pair<ll,int>> pq, pq1;
ll seg[Max];
void Update(int x, int l, int r, int pos) {
if(l == r) {
seg[x] = 1;
}
else {
int mid = (l+r)/2;
if(pos <= mid) Update(x*2,l,mid,pos);
else Update(x*2+1,mid+1,r,pos);
seg[x] = seg[x*2]+seg[x*2+1];
}
}
int sum(int x, int l, int r, int L, int R) {
if(L <= l && r <= R) {
return seg[x];
}
else if(l > R || r < L) {
return 0;
}
else {
int mid = (l+r)/2;
return sum(x*2,l,mid,L,R)+sum(x*2+1,mid+1,r,L,R);
}
}
int main()
{
ios_base::sync_with_stdio(0); cout.tie(0); cin.tie(0);
int n, m; cin >> n >> m;
for(int i = 0; i < n; i++) {
cin >> a[i] >> b[i];
mn.push_back({min(a[i],b[i]),i});
mx.push_back({-max(b[i],a[i]),i});
}
sort(mn.begin(),mn.end());
sort(mx.begin(),mx.end());
for(int i = 0; i < m; i++) {
int x; cin >> x;
pq.push({-x,i});
pq1.push({x,i});
}
ll ans = 0;
for(int i = 0; i < mn.size(); i++) {
while(!pq.empty() && -pq.top().fi < mn[i].fi) pq.pop();
if(!pq.empty() && -pq.top().fi < max(a[mn[i].se],b[mn[i].se])) pos[mn[i].se] = pq.top().se;
else if(!pq.empty()) pos[mn[i].se] = -1;
}
for(int i = 0; i < mx.size(); i++) {
// cout << -mx[i].fi << 'p' << endl;
while(!pq1.empty() && -mx[i].fi <= pq1.top().fi) {
// cout << pq1.top().fi << 'h' << endl;
// cout << pq1.top().se << 'f' << endl;
Update(1,0,m,pq1.top().se);
pq1.pop();
}
int cnt = sum(1,0,m,pos[mx[i].se]+1,m);
// cout << a[mx[i].se] << ' ' << b[mx[i].se] << ' ' << pos[mx[i].se] << ' ' << cnt << endl;
if(pos[mx[i].se] == -1 && cnt%2 == 0) ans += a[mx[i].se];
else if(pos[mx[i].se] == -1 && cnt%2 == 1) ans += b[mx[i].se];
else if(cnt%2 == 0) ans += max(a[mx[i].se],b[mx[i].se]);
else ans += min(a[mx[i].se],b[mx[i].se]);
}
cout << ans << endl;
return 0;
}
