#include <bits/stdc++.h>
using namespace std;
/// https://codeforces.com/blog/entry/12781?#comment-175184
bool cmp(array<int, 2>a, array<int, 2>b){
return max(a[0], a[1]) < max(b[0], b[1]);
}
struct SegmentTree{
vector<int>sTree;
SegmentTree(int n){
sTree.resize(4 * n);
}
void Build(int node, int l, int r, vector<int>&v){
if(l == r){
sTree[node] = v[l];
}
else{
int mid = (l + r) / 2;
Build(node * 2, l, mid, v);
Build(node * 2 + 1, mid + 1, r, v);
sTree[node] = max(sTree[node * 2], sTree[node * 2 + 1]);
}
}
int Query(int node, int l, int r, int ql, int qr){
if(ql > r || l > qr){
return 0;
}
if(ql <= l && r <= qr){
return sTree[node];
}
int mid = (l + r) / 2;
int lc = Query(node * 2, l, mid, ql, qr);
int rc = Query(node * 2 + 1, mid + 1, r, ql, qr);
return max(lc, rc);
}
};
struct BIT{
vector<int>fen;
int sz;
BIT(int n){
fen.resize(n + 1);
sz = n;
}
void Update(int pos, int val){
while(pos <= sz){
fen[pos] += val;
pos += (pos & -pos);
}
}
int Sum(int pos){
int s = 0;
while(pos > 0){
s += fen[pos];
pos -= (pos & -pos);
}
return s;
}
};
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, q;
cin >> n >> q;
vector<array<int, 2>>v(n), ev;
vector<int>t(q + 1), compress = {-1};
vector<int>pos(2 * n + q);
for(int i = 0;i < n;++i){
cin >> v[i][0] >> v[i][1];
compress.push_back(v[i][0]);
compress.push_back(v[i][1]);
}
for(int i = 1;i <= q;++i){
cin >> t[i];
compress.push_back(t[i]);
}
sort(compress.begin(), compress.end());
compress.erase(unique(compress.begin(), compress.end()), compress.end());
for(int i = 0;i < n;++i){
int p = lower_bound(compress.begin(), compress.end(), v[i][0]) - compress.begin();
v[i][0] = p;
p = lower_bound(compress.begin(), compress.end(), v[i][1]) - compress.begin();
v[i][1] = p;
}
for(int i = 1;i <= q;++i){
int p = lower_bound(compress.begin(), compress.end(), t[i]) - compress.begin();
t[i] = p;
pos[t[i]] = max(pos[t[i]], i);
ev.push_back({t[i], i});
}
sort(ev.begin(), ev.end());
sort(v.begin(), v.end(), cmp);
SegmentTree tree(2 * n + q);
tree.Build(1, 1, 2 * n + q, pos);
BIT cnt(q);
int p = (int)ev.size() - 1;
long long res = 0;
for(int i = n - 1;i >= 0;--i){
while(p >= 1 && max(v[i][0], v[i][1]) <= ev[p][0]){
cnt.Update(ev[p][1], 1);
p--;
}
int indx = tree.Query(1, 1, 2 * n + q, min(v[i][0], v[i][1]), max(v[i][0], v[i][1]) - 1);
int f = cnt.Sum(q) - cnt.Sum(indx);
if(indx && v[i][0] < v[i][1])f++;
f %= 2;
res += compress[v[i][f]];
}
cout << res << '\n';
}
