#include <bits/stdc++.h>
using namespace std;
const int N = 200200;
const int T = 600000;
int n, k, a[N], b[N], c[N], t[T * 4 + 1007], ts[T * 4 + 1007];
vector<int> ns;
int pts (int x){
return lower_bound(ns.begin(), ns.end(), x) - ns.begin() + 1;
}
void upd (int id, int l, int r, int k, int x){
if (l == r){
t[id] = x;
return;
}
int m = l + r >> 1;
if (k <= m){
upd(id * 2, l, m, k, x);
} else {
upd(id * 2 + 1, m + 1, r, k, x);
}
t[id] = max(t[id * 2], t[id * 2 + 1]);
return;
}
int get (int id, int l, int r, int u, int v){
if (l > v || r < u){
return 0;
}
if (l >= u && r <= v){
return t[id];
}
int m = l + r >> 1;
return max(get(id * 2, l, m, u, v), get(id * 2 + 1, m + 1, r, u, v));
}
void upds (int id, int l, int r, int k){
if (l == r){
++ts[id];
return;
}
int m = l + r >> 1;
if (k <= m){
upds(id * 2, l, m, k);
} else {
upds(id * 2 + 1, m + 1, r, k);
}
ts[id] = ts[id * 2] + ts[id * 2 + 1];
return;
}
int gets (int id, int l, int r, int u, int v){
if (l > v || r < u){
return 0;
}
if (l >= u && r <= v){
return ts[id];
}
int m = l + r >> 1;
return gets(id * 2, l, m, u, v) + gets(id * 2 + 1, m + 1, r, u, v);
}
int32_t main (){
ios::sync_with_stdio(false); cin.tie(nullptr);
if (fopen ("test.inp", "r")){
freopen ("test.inp", "r", stdin);
freopen ("test.out", "w", stdout);
}
cin >> n >> k;
for (int i = 1; i <= n; ++i){
cin >> a[i] >> b[i];
ns.push_back(a[i]);
ns.push_back(b[i]);
}
for (int i = 1; i <= k; ++i){
cin >> c[i];
ns.push_back(c[i]);
}
sort(ns.begin(), ns.end());
ns.erase(unique(ns.begin(), ns.end()), ns.end());
for (int i = 1; i <= n; ++i){
a[i] = pts(a[i]);
b[i] = pts(b[i]);
}
for (int i = 1; i <= k; ++i){
c[i] = pts(c[i]);
upd(1, 1, T, c[i], i);
}
vector<tuple<int, int, int>> events;
for (int i = 1; i <= n; ++i){
int x = min(a[i], b[i]), y = max(a[i], b[i]);
int f = get(1, 1, T, x, y - 1);
if (f != 0){
events.push_back({f, y, x});
} else {
events.push_back({f, a[i], b[i]});
}
}
sort(events.begin(), events.end(), greater<tuple<int, int, int>>());
int id = k + 1;
long long ans = 0;
for (auto [f, x, y] : events){
while (id > f && id > 1){
upds(1, 1, T, c[--id]);
}
int flip = gets(1, 1, T, max(x, y), T);
ans += 1ll * ns[(flip % 2 == 0 ? x : y) - 1];
}
cout << ans << "\n";
}
