#include <bits/stdc++.h>
#define ii pair<int, int>
#define fi first
#define se second
#define siz(v) ((int)(v).size())
#define all(v) begin((v)), end(v)
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(i) (1LL << (i))
#define dbg(x) "[" #x " = " << x << "]"
#define lli pair<long long, int>
#define FOR(i, a, b) for (int (i) = (a); (i) <= (b); (i)++)
#define FOD(i, a, b) for (int (i) = (b); (i) >= (a); (i)--)
#define REP(i, n) for(int (i) = 0; (i) < n; (i)++)
using namespace std;
bool M1;
const int infINT = 1e9 + 123;
const long long inf = 1e18 + 12;
const int mod = 998244353;
template<class X, class Y> bool minimize(X &x, const Y &y){return x > y ? x = y, 1: 0;}
template<class X, class Y> bool maximize(X &x, const Y &y){return x < y ? x = y, 1: 0;}
void add(int &a, const int &b){
a += b;
if (a >= mod) a -= mod;
}
int mul(const int &a, const int &b){
return 1LL * a * 1LL * b % mod;
}
const int dx[4] = {-1, +1, +2, +2};
const int dy[4] = {+2, +2, +1, -1};
const int MAXN = 2e5 + 5;
struct segmentTree{
int n;
vector<int > mx;
segmentTree(int _n = 0): n(_n){
mx.assign(n << 1 | 1, 0);
}
void update(int pos, const int &val){
pos--;
pos += n;
mx[pos] = val;
while(pos > 1){
pos >>= 1;
mx[pos] = max(mx[pos << 1], mx[pos << 1 | 1]);
}
}
int get(int l, int r){
l--;
l += n; r += n;
int best = 0;
while(l < r){
if (l & 1) maximize(best, mx[l++]);
if (r & 1) maximize(best, mx[--r]);
l >>= 1; r >>= 1;
}
return best;
}
};
struct fenwickTree{
int n;
vector<int > bit;
fenwickTree(int _n = 0): n(_n){
bit.assign(n + 1, 0);
}
void update(int pos, const int &delta){
for(; pos > 0; pos ^= pos & -pos) bit[pos] += delta;
}
int get(int pos){
int sum = 0;
for(; pos <= n; pos += pos & -pos) sum += bit[pos];
return sum;
}
};
int numVal, numQuery, A[MAXN], B[MAXN], query[MAXN], cnt[MAXN];
bool special[MAXN];
vector<int > comp, can[MAXN * 3];
void input(){
cin >> numVal >> numQuery;
FOR(i, 1, numVal){
cin >> A[i] >> B[i];
special[i] = 1;
if (A[i] > B[i]) swap(A[i], B[i]), special[i] = 0;
comp.push_back(A[i]);
comp.push_back(B[i] - 1);
}
FOR(q, 1, numQuery){
cin >> query[q];
comp.push_back(query[q]);
}
}
int getPos(const int &pos){
return lower_bound(all(comp), pos) - begin(comp) + 1;
}
void solve(){
sort(all(comp));
comp.resize(unique(all(comp)) - begin(comp));
segmentTree it(siz(comp));
FOR(q, 1, numQuery){
query[q] = getPos(query[q]);
it.update(query[q], q);
}
FOR(i, 1, numVal){
A[i] = getPos(A[i]);
B[i] = getPos(B[i] - 1);
can[it.get(A[i], B[i]) + 1].push_back(i);
}
fenwickTree bit(siz(comp));
FOD(q, 1, numQuery){
bit.update(query[q], +1);
for(int id: can[q]){
cnt[id] = bit.get(B[id] + 1);
}
}
long long sum = 0;
FOR(id, 1, numVal){
if (it.get(A[id], B[id]) == 0) cnt[id] += special[id];
if (cnt[id] % 2) sum += comp[A[id] - 1];
else sum += comp[B[id] - 1] + 1;;
}
cout << sum << '\n';
cerr << sum << '\n';
}
bool M2;
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define task "test"
if (fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
int t = 1;
// cin >> t;
while(t--){
input();
solve();
}
cerr << (1.0 * clock()) / CLOCKS_PER_SEC << ".s\n";
cerr << (&M2 - &M1) / 1048576 << " mb\n";
}
