#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define all(v) begin(v), end(v)
#define pi pair<int, int>
#define vi vector<int>
using namespace std;
struct BIT {
int n;
vector<int> bit;
BIT(int n=0): n(n), bit(n+1, 0) {}
void add(int i, int v = 1) { for (; i <= n; i += i & -i) bit[i] += v; }
int sum(int i) { int s = 0; for (; i > 0; i -= i & -i) s += bit[i]; return s; }
};
struct Seg {
int n;
vector<int> seg;
Seg(int m = 0) { init(m); }
void init(int m) {
n = 1;
while (n < m) n <<= 1;
seg.assign(2*n, 0);
}
void set_leaf(int idx, int val) {
int p = idx + n;
seg[p] = val;
for (p >>= 1; p; p >>= 1) seg[p] = max(seg[p<<1], seg[p<<1|1]);
}
int range_max(int l, int r) {
if (l > r) return 0;
l += n; r += n;
int res = 0;
while (l <= r) {
if (l & 1) res = max(res, seg[l++]);
if (!(r & 1)) res = max(res, seg[r--]);
l >>= 1; r >>= 1;
}
return res;
}
};
struct Query {
ll L;
int pos;
int id;
bool hasM;
ll s, l;
ll orig;
};
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
int n, k; cin>>n>>k;
vector<ll> a(n+1), b(n+1);
for (int i = 1; i <= n; ++i) cin >> a[i] >> b[i];
vector<ll> t(k+1);
for (int j = 1; j <= k; ++j) cin >> t[j];
vector<ll> vals;
vals.reserve(k);
for (int j = 1; j <= k; ++j) vals.push_back(t[j]);
sort(vals.begin(), vals.end());
vals.erase(unique(vals.begin(), vals.end()), vals.end());
int m = (int)vals.size();
vector<int> lastPos(m, 0);
for (int j = 1; j <= k; ++j) {
int idx = int(lower_bound(vals.begin(), vals.end(), t[j]) - vals.begin());
lastPos[idx] = max(lastPos[idx], j);
}
Seg st(m);
for (int i = 0; i < m; ++i) st.set_leaf(i, lastPos[i]);
vector<Query> qs;
for (int i = 1; i <= n; ++i) {
ll s = min(a[i], b[i]);
ll l = max(a[i], b[i]);
int lo = int(lower_bound(vals.begin(), vals.end(), s) - vals.begin());
int hi = int(upper_bound(vals.begin(), vals.end(), l - 1) - vals.begin()) - 1;
int lastM = 0;
bool hasM = false;
if (lo <= hi && lo < m && hi >= 0) {
lastM = st.range_max(max(0, lo), min(m-1, hi));
if (lastM > 0) hasM = true;
}
int pos = hasM ? lastM : 0;
qs.push_back({l, pos, i, hasM, s, l, a[i]});
}
vector<pair<ll,int>> ops;
ops.reserve(k);
for (int j = 1; j <= k; ++j) ops.emplace_back(t[j], j);
sort(ops.begin(), ops.end(), greater<>());
vector<int> order(n);
iota(order.begin(), order.end(), 0);
sort(order.begin(), order.end(), [&](int x, int y) {
if (qs[x].L != qs[y].L) return qs[x].L > qs[y].L;
return qs[x].pos < qs[y].pos;
});
BIT bit(k);
ll added = 0;
int p = 0;
vector<ll> cntAfter(n+1, 0);
for (int idx : order) {
ll need = qs[idx].L;
while (p < (int)ops.size() && ops[p].first >= need) {
bit.add(ops[p].second, 1);
++added;
++p;
}
int jpos = qs[idx].pos;
ll cnt = added - bit.sum(jpos);
cntAfter[qs[idx].id] = cnt;
}
ll ans = 0;
for (int i = 1; i <= n; ++i) {
auto &q = qs[i-1];
ll s = q.s, l = q.l;
ll cnt = cntAfter[i];
ll finalv;
if (q.hasM) finalv = (cnt % 2 == 0) ? l : s;
else finalv = (cnt % 2 == 0) ? q.orig : ((q.orig == s) ? l : s);
ans += finalv;
}
cout << ans;
return 0;
}
