#include <cstdio>
#include <algorithm>
#include <vector>
#include <iostream>
using namespace std;
const int MAXN = 200050, MAXK = 200050, MAXV = 2 * MAXN + MAXK;
int N, K, M;
int A[MAXN], B[MAXN], T[MAXK], X[MAXV];
pair<int, int> J[MAXN];
vector<int> S[MAXV * 4 + 50];
void insert(int x, int u, int a, int b, int L, int R) {
if (a == L && b == R) {
S[x].push_back(u);
return;
}
int m = (L + R) / 2;
if (a < m) insert(2 * x + 0, u, a, min(b, m), L, m);
if (b > m) insert(2 * x + 1, u, max(a, m), b, m, R);
}
void check(int x, int j, int t, int L, int R) {
for (int i = 0; i < S[x].size(); ++i) {
if (J[S[x][i]].first < 0) {
J[S[x][i]].first = j;
}
}
S[x].clear();
if (R - L == 1) {
return;
}
int m = (L + R) / 2;
if (t < m) check(2 * x + 0, j, t, L, m);
else check(2 * x + 1, j, t, m, R);
return;
}
int F[MAXV];
void update(int x) {
while (x <= M) {
++F[x];
x += x & -x;
}
}
int sum(int x) {
int s = 0;
while (x > 0) {
s += F[x];
x -= x & -x;
}
return s;
}
int main() {
scanf("%d%d", &N, &K);
int xs = 0;
for (int i = 0; i < N; ++i) {
scanf("%d%d", &A[i], &B[i]);
X[xs++] = A[i];
X[xs++] = B[i];
}
for (int j = 0; j < K; ++j) {
scanf("%d", &T[j]);
X[xs++] = T[j];
}
sort(X, X + xs);
M = unique(X, X + xs) - X;
for (int i = 0; i < N; ++i) {
A[i] = lower_bound(X, X + M, A[i]) - X;
B[i] = lower_bound(X, X + M, B[i]) - X;
J[i] = make_pair(-1, i);
insert(1, i, min(A[i], B[i]), max(A[i], B[i]), 0, M);
}
for (int j = K - 1; j >= 0; --j) {
T[j] = lower_bound(X, X + M, T[j]) - X;
check(1, j, T[j], 0, M);
}
sort(J, J + N);
reverse(J, J + N);
int cur = K - 1, all = 0;
long long res = 0;
for (int i = 0; i < N; ++i) {
while (cur > J[i].first) {
update(T[cur--] + 1);
++all;
}
int u = J[i].second;
int flip = (all - sum(B[u])) % 2;
int start = cur >= 0 ? (A[u] < B[u] ? 1 : 0) : 0;
res += X[(start + flip) % 2 ? B[u] : A[u]];
}
printf("%lld\n", res);
return 0;
}
