#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int INF = (int) 1e9 + 1e6 + 123;
const ll LINF = (ll) 1e18 + 1e9 + 123;
#define rep(i, s, t) for (auto i = (s); i < (t); ++(i))
#define per(i, s, t) for (auto i = (s); i >= (t); --(i))
#define sz(x) ((int)(x).size())
#define mp make_pair
#define pb push_back
#define all(x) (x).begin(), (x).end()
bool mini(auto &x, const auto &y) {
if (y < x) {
x = y;
return 1;
}
return 0;
}
bool maxi(auto &x, const auto &y) {
if (y > x) {
x = y;
return 1;
}
return 0;
}
void run();
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
run();
return 0;
}
const int N = 1 << 18;
int n, k;
int a[N], b[N];
pair<int, int> op[N];
int sum[2 * N], mi[2 * N];
void upd(int i, int v) {
i += N;
sum[i] = 1;
mi[i] = v;
i /= 2;
while (i) {
sum[i] = sum[2 * i] + sum[2 * i + 1];
mi[i] = min(mi[2 * i], mi[2 * i + 1]);
i /= 2;
}
}
int get(int i, int tl, int tr, int l, int r) {
if (tl >= r || tr <= l) {
return 0;
}
if (l <= tl && tr <= r) {
return sum[i];
}
int tm = (tl + tr) / 2;
return get(2 * i, tl, tm, l, r) + get(2 * i + 1, tm, tr, l, r);
}
int find(int i, int tl, int tr, int l, int r, int v) {
if (tl >= r || tr <= l || mi[i] >= v) {
return -1;
}
if (tl == tr - 1) {
return tl;
}
int tm = (tl + tr) / 2;
int res = find(2 * i + 1, tm, tr, l, r, v);
if (res != -1) {
return res;
}
return find(2 * i, tl, tm, l, r, v);
}
void run() {
cin >> n >> k;
rep(i, 0, n) {
cin >> a[i] >> b[i];
}
rep(i, 0, k) {
cin >> op[i].first;
op[i].second = i;
}
sort(op, op + k);
vector<int> p(n);
rep(i, 0, n) {
p[i] = i;
}
sort(all(p), [] (int i, int j) {
return min(a[i], b[i]) > min(a[j], b[j]);
});
int ptr = k - 1;
rep(i, 0, 2 * N) {
mi[i] = INF;
}
ll ans = 0;
rep(ii, 0, n) {
int i = p[ii];
while (ptr >= 0 && op[ptr].first >= min(a[i], b[i])) {
upd(op[ptr].second, op[ptr].first);
ptr--;
}
int pos = find(1, 0, N, 0, N, max(a[i], b[i]));
if (pos != -1 && a[i] < b[i]) {
swap(a[i], b[i]);
}
int cnt = get(1, 0, N, pos + 1, N);
ans += (cnt % 2 ? b[i] : a[i]);
}
cout << ans << "\n";
}
