#include <bits/stdc++.h>
#define FOR(i, x, y) for (int i = x; i < y; i++)
typedef long long ll;
using namespace std;
int n, q;
pair<int, int> a[200001];
int t[200001], segtree[2400001], bit[600001];
vector<pair<int, int>> c;
bool inv[200001], visited[200001];
void build(int node = 1, int l = 0, int r = 2 * n + q - 1) {
if (l == r) segtree[node] = max(c[l].second, 0);
else {
int mid = (l + r) / 2;
build(node * 2, l, mid);
build(node * 2 + 1, mid + 1, r);
segtree[node] = max(segtree[node * 2], segtree[node * 2 + 1]);
}
}
int rmq(int x, int y, int node = 1, int l = 0, int r = 2 * n + q - 1) {
if (l > y || r < x) return 0;
if (l >= x && r <= y) return segtree[node];
int mid = (l + r) / 2;
return max(rmq(x, y, node * 2, l, mid), rmq(x, y, node * 2 + 1, mid + 1, r));
}
void add(int pos) { for (; pos <= q; pos += (pos & (-pos))) bit[pos]++; }
int rsq(int x, int y) {
int ans = 0;
for (; y; y -= (y & (-y))) ans += bit[y];
for (x--; x; x -= (x & (-x))) ans -= bit[x];
return ans;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> q;
FOR(i, 1, n + 1) {
cin >> a[i].first >> a[i].second;
inv[i] = a[i].first < a[i].second;
if (inv[i]) swap(a[i].first, a[i].second);
c.push_back({a[i].first, -i});
c.push_back({a[i].second, -i});
}
FOR(i, 1, q + 1) {
cin >> t[i];
c.push_back({t[i], i});
}
sort(c.begin(), c.end());
build();
FOR(i, 1, n + 1) {
a[i].first = lower_bound(c.begin(), c.end(), make_pair(a[i].first, -i)) - c.begin();
a[i].second = lower_bound(c.begin(), c.end(), make_pair(a[i].second, -i)) - c.begin();
}
ll ans = 0;
for (int i = c.size() - 1; i; i--) {
int k = c[i].second;
if (k < 0) {
k *= -1;
if (visited[k]) continue;
visited[k] = true;
int mn = rmq(a[k].second, a[k].first);
int cnt = rsq(mn + 1, q) + (mn == 0 && inv[k]);
if (cnt & 1) ans += c[a[k].second].first;
else ans += c[a[k].first].first;
} else add(k);
}
cout << ans;
return 0;
}
