#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <algorithm>
#include <random>
#include <iomanip>
#include <functional>
#include <cassert>
using namespace std;
typedef long long ll;
struct SegmentTree {
int n;
vector <int> t;
SegmentTree(int nn) {
n = nn;
t.resize(4 * n, -1);
}
void modify(int i, int val, int l, int r, int v) {
if (l == r) {
t[v] = max(t[v], val);
} else {
int m = (l + r) >> 1;
if (i <= m) modify(i, val, l, m, 2 * v + 1);
else modify(i, val, m + 1, r, 2 * v + 2);
t[v] = max(t[2 * v + 1], t[2 * v + 2]);
}
}
int get(int ql, int qr, int l, int r, int v) {
if (qr < l || r < ql) return -1;
if (ql <= l && r <= qr) return t[v];
int m = (l + r) >> 1;
return max(get(ql, qr, l, m, 2 * v + 1), get(ql, qr, m + 1, r, 2 * v + 2));
}
};
int main() {
ios_base::sync_with_stdio(false); cin.tie(0);
#ifdef LOCAL
freopen("input.txt", "r", stdin);
#endif
int n, k;
cin >> n >> k;
vector <int> a(n), b(n);
vector <int> c;
for (int i = 0; i < n; ++i) {
cin >> a[i] >> b[i];
c.push_back(a[i]);
c.push_back(b[i]);
}
vector <int> t(k);
for (int i = 0; i < k; ++i) {
cin >> t[i];
c.push_back(t[i]);
}
sort(c.begin(), c.end());
c.resize(unique(c.begin(), c.end()) - c.begin());
for (int i = 0; i < n; ++i) {
a[i] = lower_bound(c.begin(), c.end(), a[i]) - c.begin();
b[i] = lower_bound(c.begin(), c.end(), b[i]) - c.begin();
}
for (int i = 0; i < k; ++i) {
t[i] = lower_bound(c.begin(), c.end(), t[i]) - c.begin();
}
int m = c.size();
SegmentTree st(m);
for (int i = 0; i < k; ++i) {
st.modify(t[i], i, 0, m - 1, 0);
}
vector <int> when(n, -1);
for (int i = 0; i < n; ++i) {
int mn = min(a[i], b[i]);
int mx = max(a[i], b[i]);
if (mn < mx) {
when[i] = st.get(mn, mx - 1, 0, m - 1, 0);
}
}
ll ans = 0;
for (int i = 0; i < n; ++i) {
int st = 0;
int go = when[i] + 1;
if (when[i] != -1 && b[i] > a[i]) {
st = 1;
}
for (int j = go; j < k; ++j) {
if (a[i] <= t[j] && b[i] <= t[j]) {
st ^= 1;
}
}
if (st == 0) ans += c[a[i]];
else ans += c[b[i]];
}
cout << ans << '\n';
}
