#include<bits/stdc++.h>
#define f first
#define s second
#define int long long
#define pii pair<int,int>
using namespace std;
const int N = 2e5 + 5, mod = 1e9 + 7; // !
int fw[N], a[N], b[N], c[N], t[4 * N], m;
vector<int> X[N];
void upd(int id) {
for(id; id <= m; id += id & (-id)) fw[id] ^= 1;
}
int get(int id) {
int ans = 0;
for(id; id >= 1; id -= id & (-id)) ans ^= fw[id];
return ans;
}
bool cmp(int x, int y) {
return (max(a[x], b[x]) < max(a[y], b[y]));
}
int merge(int i, int j) {
return (max(a[i], b[i]) >= max(a[j], b[j]) ? i : j);
}
void build(int u, int l, int r) {
if(l == r) {
t[u] = (X[l].size() ? X[l].back() : 0);
return;
}
int mid = (l + r) / 2;
build(2 * u, l, mid); build(2 * u + 1, mid + 1, r);
t[u] = merge(t[2 * u], t[2 * u + 1]);
}
void rem(int u, int id, int l, int r) {
if(l > id || r < id) return;
if(l == r) {
X[l].pop_back();
t[u] = (X[l].size() ? X[l].back() : 0);
return;
}
int mid = (l + r) / 2;
rem(2 * u, id, l, mid); rem(2 * u + 1, id, mid + 1, r);
t[u] = merge(t[2 * u], t[2 * u + 1]);
}
int get(int u, int st, int en, int l, int r) {
if(l > en || r < st) return 0;
if(st <= l && r <= en) return t[u];
int mid = (l + r) / 2;
return merge(get(2 * u, st, en, l, mid), get(2 * u + 1, st, en, mid + 1, r));
}
main(){
int n, k;
cin >> n >> k;
vector<int> x;
vector<int> A(n + 1), B(n + 1);
for(int i = 1; i <= n; i++) {
cin >> a[i] >> b[i];
A[i] = a[i]; B[i] = b[i];
x.push_back(a[i]);
x.push_back(b[i]);
}
for(int i = 1; i <= k; i++) {
cin >> c[i];
x.push_back(c[i]);
}
sort(x.begin(), x.end());
x.erase(unique(x.begin(), x.end()), x.end());
for(int i = 1; i <= n; i++)
a[i] = lower_bound(x.begin(), x.end(), a[i]) - x.begin() + 1,
b[i] = lower_bound(x.begin(), x.end(), b[i]) - x.begin() + 1,
X[min(a[i], b[i])].push_back(i);
for(int i = 1; i <= x.size(); i++) sort(X[i].begin(), X[i].end(), cmp);
build(1, 1, x.size());
m = x.size();
int ans = 0;
for(int i = k; i >= 0; i--) {
c[i] = lower_bound(x.begin(), x.end(), c[i]) - x.begin() + 1;
while(true) {
int id = get(1, 1, (!i ? m : c[i]), 1, m);
if(max(a[id], b[id]) > (!i ? 0 : c[i])) {
if(i) ans += (get(min(a[id], b[id])) ? min(A[id], B[id]) : max(A[id], B[id]));
else ans += (get(min(a[id], b[id])) == 0 ? A[id] : B[id]);
rem(1, min(a[id], b[id]), 1, m);
} else break;
}
upd(1);
upd(c[i] + 1);
}
cout << ans;
}
