#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 Fenwick{
int n; vector<vector<ll>> t;
void resize(int _n){
n = _n;
t.assign(n+1, vector<ll>(2, 0));
}
void upd(int tp, int id, ll x){
for(int i = id; i <= n; i+=i&(-i)) t[i][tp]+=x;
}
void add(int l, int r, ll x){
upd(0, l, x); upd(0, r+1, -x);
upd(1, l, x*(l-1)); upd(1, r+1, -x*r);
}
ll sum(int tp, int id){
ll res = 0;
for(int i = id; i > 0; i-=i&(-i)) res+=t[i][tp];
return res;
}
ll get(int x){
return sum(0, x)*(ll)x - sum(1, x);
}
ll query(int a, int b){
return get(b) - get(a-1);
}
};
const int N = 2e5+3;
int n, k, t[N];
pair<pair<int, int>, int> a[N];
Fenwick f;
int sr[N];
int tr[N*4]; //min on segment
void update(int id, int l, int r, int u, int v){
if(u < l || r < u) return ;
if(l == r){
tr[id] = v;
return ;
}
int mid = (l+r)/2;
update(id*2, l, mid, u, v);
update(id*2+1, mid+1, r, u, v);
tr[id] = max(tr[id*2], tr[id*2+1]);
}
int query(int id, int l, int r, int u, int v){
if(v < l || r < u) return -1e9;
if(u <= l && r <= v) return tr[id];
int mid = (l+r)/2;
return max(query(id*2, l, mid, u, v), query(id*2+1, mid+1, r, u, v));
}
int walk(int id, int l, int r, int u){
if(tr[id] < u) return -1;
if(l == r) return l;
int mid = (l+r)/2;
if(tr[id*2+1] >= u) return walk(id*2+1, mid+1, r, u);
else return walk(id*2, l, mid, u);
}
int o[N];
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> k;
for(int i = 1; i <= n; i++){
cin >> a[i].first.first >> a[i].first.second;
a[i].second = a[i].first.first;
if(a[i].first.first > a[i].first.second) swap(a[i].first.first, a[i].first.second);
}
for(int i = 1; i <= k; i++) cin >> t[i];
sort(a+1, a+n+1, [&](pair<pi, int> a, pair<pi, int> b){
return a.first.second > b.first.second;
});
for(int i = 1; i <= k; i++) sr[i] = i;
for(int i = 1; i <= k; i++) update(1, 1, k, i, t[i]);
sort(sr+1, sr+k+1, [&](int a, int b){
return t[a] > t[b];
});
f.resize(k);
int pt = 1; ll res = 0;
for(int i = 1; i <= n; i++){
//update all b[i] <= t[...]
while(pt <= k && t[sr[pt]] >= a[i].first.second){
f.add(sr[pt], sr[pt], 1);
update(1, 1, k, sr[pt], -1);
pt++;
}
//first id so a[i] <= t[id]
int id = walk(1, 1, k, a[i].first.first), cnt, add;
if(id == -1){
//all a[i] >= t[id]
cnt = f.query(1, k);
if(cnt & 1) add = a[i].second ^ a[i].first.first ^ a[i].first.second;
else add = a[i].second;
}
else{
cnt = f.query(id+1, k);
if(cnt & 1) add = a[i].first.first;
else add = a[i].first.second;
}
res += add;
// cout << a[i].first.first << " " << a[i].first.second << " " << a[i].second << "\n";
// for(int i = 1; i <= k; i++) cout << query(1, 1, k, i, i) << " ";
// cout << "\n";
// for(int i = 1; i <= k; i++) cout << f.query(i, i) << " ";
// cout << "\n";
// cout << id << " " << cnt << " " << add << "\n\n";
}
cout << res;
return 0;
}
