// Alir3za.Zar3 -> Shiraz , Iran
#include <bits/stdc++.h>
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//#define int long long
const int maxn = 6e5+7;
int n,k , a[maxn],b[maxn],t[maxn];
struct SEGMENT
{
int T[maxn<<2] = {};
void update
(int id , int v , int node=1 , int l=0 , int r=maxn)
{
if (l+1 == r)
{
T[node] = v;
return;
}
int o=l+r>>1 , lc=node<<1 , rc=lc|1;
if (id<o) update(id , v , lc , l , o);
else update(id , v , rc , o , r);
T[node] = max(T[lc] , T[rc]);
}
int query
(int lq , int rq , int node=1 , int l=0 , int r=maxn)
{
if (r<=lq or l>=rq) return 0;
if (lq<=l and r<=rq) return T[node];
int o=l+r>>1 , lc=node<<1 , rc=lc|1;
return max( query(lq , rq , lc , l , o),
query(lq , rq , rc , o , r));
}
} seg;
struct FENWICK
{
int bit[maxn];
void update (int id)
{
for (; id<maxn; id+=id&-id)
bit[id]++;
}
int query (int id)
{
int out = 0;
for (; id; id-=id&-id)
out += bit[id];
return out;
}
} fen;
signed main ()
{
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cin >> n >> k;
vector<int> comp;
for (int i=1; i<=n; i++)
{
cin >> a[i] >> b[i];
comp.push_back(a[i]);
comp.push_back(b[i]);
}
for (int i=1; i<=k; i++)
{
cin >> t[i];
comp.push_back(t[i]);
}
sort(comp.begin() , comp.end());
comp.resize(unique(comp.begin(),comp.end())-comp.begin());
unordered_map<int , int> mp , mq;
int sz = comp.size();
for (int i=0; i<sz; i++)
mp[comp[i]] = i+1 , mq[i+1] = comp[i];
set<pair<int,int> , greater<pair<int,int>>> pq;
for (int i=1; i<=k; i++)
seg.update(mp[t[i]] , i),
pq.insert({mp[t[i]] , i});
vector<pair<int,int>> q;
for (int i=1; i<=n; i++)
a[i] = mp[a[i]] , b[i] = mp[b[i]],
q.push_back({max(a[i] , b[i]) , i});
sort(q.begin() , q.end() , greater<pair<int,int>>());
int out = 0;
for (auto [s , id] : q)
{
while (!pq.empty())
{
auto [v , T] = *pq.begin();
if (v < s) break;
pq.erase(pq.begin());
fen.update(T);
}
int z = (a[id]==b[id] ? 0:seg.query(min(a[id] , b[id]) , s));
int val = fen.query(maxn-1)-(z?fen.query(z):0);
if (z == 0)
if (val%2) out += mq[b[id]];
else out += mq[a[id]];
else
if (val%2 == 0) out += mq[s];
else out += min(mq[a[id]] , mq[b[id]]);
}
cout << out << '\n';
}
