#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ff first
#define ss second
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define N 200005
#define INF 0x3f3f3f3f3f3f3f3f
#define MOD 1000000007LL
int s[N][2];
int t[N];
vector<int> seg[N << 2];
void build(int id, int l, int r){
if(l == r){
seg[id].push_back(t[l]);
return;
}
int i1 = 0, i2 = 0, id1 = id << 1, id2 = id << 1 | 1, s1, s2;
int m = (l + r) >> 1;
build(id1, l, m);
build(id2, m + 1, r);
s1 = seg[id1].size();
s2 = seg[id2].size();
while(i1 != s1 && i2 != s2){
if(seg[id1][i1] > seg[id2][i2])
seg[id].push_back(seg[id2][i2++]);
else
seg[id].push_back(seg[id1][i1++]);
}
while(i1 != s1)
seg[id].push_back(seg[id1][i1++]);
while(i2 != s2)
seg[id].push_back(seg[id2][i2++]);
}
pair<int, int> query(int id, int l, int r, int f, int s){
auto it = lower_bound(seg[id].begin(), seg[id].end(), min(f, s));
if(it == seg[id].end())
return {0, 0};
if(*it >= max(f, s))
return {0, seg[id].end() - it};
if(l == r)
return {1, 0};
int m = (l + r) >> 1;
auto r2 = query(id << 1 | 1, m + 1, r, f, s);
if(r2.ff == 1) return r2;
auto r1 = query(id << 1, l, m, f, s);
return {r1.ff, r1.ss ^ r2.ss};
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, k;
cin>>n>>k;
for(int i = 1; i <= n; i++)
cin>>s[i][0]>>s[i][1];
for(int i = 1; i <= k; i++)
cin>>t[i];
build(1, 1, k);
ll res = 0;
for(int i = 1; i <= n; i++){
auto w = query(1, 1, k, s[i][0], s[i][1]);
if(w.ff)
if(s[i][0] < s[i][1])
swap(s[i][0], s[i][1]);
res += s[i][w.ss & 1];
}
cout<<res;
}
