#include <bits/stdc++.h>
using namespace std;
const int MXN = 200 * 1000 + 3;
int tree[MXN << 2], a[MXN], b[MXN], t[MXN], oga[MXN], ogb[MXN];
vector<int> coord, q[MXN];
int n, k, sz;
function<int(int, int)> comb = [] (int x, int y) {
return max(x, y);
};
void update(int v, int tl, int tr, int pos, int x) {
if(tl == tr)
tree[v] = comb(tree[v], x);
else {
int tm = (tl + tr) >> 1;
if(pos <= tm)
update(v << 1, tl, tm, pos, x);
else
update(v << 1|1, tm + 1, tr, pos, x);
tree[v] = comb(tree[v << 1], tree[v << 1|1]);
}
}
void upd(int pos, int x) {
update(1, 1, MXN - 2, pos, x);
}
int query(int v, int tl, int tr, int l, int r) {
if(l > r)
return 0;
if(l <= tl && tr <= r)
return tree[v];
int tm = (tl + tr) >> 1;
return comb(query(v << 1, tl, tm, l, min(tm, r)),
query(v << 1|1, tm + 1, tr, max(tm + 1, l), r));
}
int query(int l, int r) {
return query(1, 1, MXN - 2, l, r);
}
signed main() {
std::ios::sync_with_stdio(0);
std::cout.tie(0);
std::cin.tie(0);
cin >> n >> k;
for(int i = 1; i <= n; i++) {
cin >> oga[i] >> ogb[i];
coord.push_back(oga[i]);
coord.push_back(ogb[i]);
}
for(int i = 1; i <= k; i++) {
cin >> t[i];
coord.push_back(t[i]);
}
sort(coord.begin(), coord.end());
coord.resize(unique(coord.begin(), coord.end()) - coord.begin());
sz = coord.size();
auto id = [&] (int x) {
return upper_bound(coord.begin(), coord.end(), x) - coord.begin();
};
for(int i = 1; i <= n; i++) {
a[i] = id(oga[i]);
b[i] = id(ogb[i]);
}
for(int i = 1; i <= k; i++) {
t[i] = id(t[i]);
upd(t[i], i);
}
for(int i = 1; i <= n; i++) {
int x = query(min(a[i], b[i]), max(a[i], b[i]) - 1);
q[x].push_back(i);
}
memset(tree, 0, sizeof tree);
comb = [&] (int x, int y) {
return x + y;
};
long long ans = 0;
for(int x = k; x >= 0; x--) {
for(int i : q[x]) {
int parity = query(max(a[i], b[i]), sz) & 1;
if(x)
parity ^= a[i] < b[i];
ans += parity ? ogb[i] : oga[i];
}
upd(t[x], 1);
}
cout << ans << '\n';
return 0;
}
