#include<bits/stdc++.h>
using namespace std;
const int N = 3 * 2 * 1000 * 100 + 10, LG = 20;
int n, k, a[N], b[N], t[N], mn[N], sz, seg[N << 2], fen[N], fl[N];
vector<int> add[N];
vector<pair<int, int>> query[N];
inline void build(int l = 0, int r = sz, int id = 1) {
if (l + 1 == r) {
seg[id] = mn[l];
return;
}
int mid = l + r >> 1;
build(l, mid, id << 1), build(mid, r, id << 1 | 1);
seg[id] = min(seg[id << 1], seg[id << 1 | 1]);
}
inline int get(int s, int e, int l = 0, int r = sz, int id = 1) {
if (s <= l && e >= r)
return seg[id];
if (s >= r || e <= l)
return k;
int mid = l + r >> 1;
return min(get(s, e, l, mid, id << 1), get(s, e, mid, r, id << 1 | 1));
}
inline void upd(int x) {
for (++x; x < N; x += x & -x)
fen[x]++;
}
inline int GET(int x) {
int res = 0;
for (; x; x -= x & -x)
res += fen[x];
return res;
}
inline int inp() {
int res = 0;
char c = '0';
while (c >= '0' && c <= '9') {
((res *= 10) += c - '0');
c = getchar();
}
return res;
}
int main() {
ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
n = inp(), k = inp();
vector<int> all;
for (int i = 0; i < n; i++) {
a[i] = inp(), b[i] = inp();
for (auto x: {a[i], b[i]})
all.push_back(x);
}
for (int i = 0; i < k; i++)
t[i] = inp(), all.push_back(t[i]);
sort(all.begin(), all.end());
all.resize(unique(all.begin(), all.end()) - all.begin());
for (int i = 0; i < n; i++)
for (auto x: {&a[i], &b[i]})
*x = lower_bound(all.begin(), all.end(), *x) - all.begin();
for (int i = 0; i < k; i++)
t[i] = lower_bound(all.begin(), all.end(), t[i]) - all.begin();
reverse(t, t + k);
sz = (int)(all.size());
for (int i = 0; i < sz; i++)
mn[i] = k;
for (int i = 0; i < k; i++)
mn[t[i]] = min(mn[t[i]], i);
build();
for (int i = 0; i < k; i++)
add[t[i]].push_back(i);
for (int i = 0; i < n; i++) {
if (a[i] > b[i])
swap(a[i], b[i]), fl[i]++;
int ind = get(a[i], b[i]);
query[b[i]].push_back({i, ind});
}
long long ans = 0;
for (int i = N - 1; i >= 0; i--) {
for (auto it: add[i])
upd(it);
for (auto it: query[i]) {
int ind = it.second, i = it.first;
int res = GET(ind);
if (ind == k) {
fl[i] += res;
} else {
fl[i] = 0;
fl[i] += res;
swap(a[i], b[i]);
}
ans += (fl[i] & 1? all[b[i]]: all[a[i]]);
}
}
printf("%lld\n", ans);
return 0;
}
