#pragma GCC optimize("O2")
#include<bits/stdc++.h>
#define fi first
#define se second
#define fo(i,a,b) for(int i=a;i<=b;++i)
#define fod(i,a,b) for(int i=a;i>=b;--i)
#define ii pair<int,int>
#define task "new"
#define ll long long
using namespace std;
const int mod=1e9+7;
const int N=2e5+5;
int n,k,a[N],b[N],t[N];
vector<int>arr,post[N*3],st[(N*3)<<2];
void build(int id,int l,int r)
{
if(l == r)
{
if(post[l].empty())
{
st[id].push_back(-1);
return ;
}
for(auto u : post[l])
st[id].push_back(u);
// if(l == 11)
// {
// for(auto u : st[id])
// cout<<u<<' ';
// cout<<'\n';
// }
//st[id].push_back(post[l] > 0 ? post[l] : -1);
return ;
}
int mid = l + r >> 1;
build(id<<1,l,mid);
build(id<<1|1,mid+1,r);
st[id].resize(st[id<<1].size() + st[id<<1|1].size());
merge(st[id<<1].begin(), st[id<<1].end(),
st[id<<1|1].begin(), st[id<<1|1].end(), st[id].begin());
}
int getmax(int id,int l,int r,int u,int v)
{
if(r < u || v < l)
return 0;
if(u <= l && r <= v)
{
return st[id].back();
}
int mid = l + r >> 1;
return max(getmax(id<<1,l,mid,u,v), getmax(id<<1|1,mid+1,r,u,v));
}
int getnum(int id,int l,int r,int u,int v,int k)
{
if(r < u || v < l)
return 0;
if(u <= l && r <= v)
{
// cout<<l<<' '<<r<<'\n';
// for(auto u : st[id])
// cout<<u<<' ';
// cout<<'\n';
int res = lower_bound(st[id].begin(),st[id].end(),k) - st[id].begin();
return st[id].size() - res;
}
int mid = l + r >> 1;
return getnum(id<<1,l,mid,u,v,k) + getnum(id<<1|1,mid+1,r,u,v,k);
}
int main()
{
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
if(fopen(task".inp","r")){
freopen(task".inp","r",stdin);
freopen(task".out","w",stdout);
}
cin>>n>>k;
fo(i,1,n)
{
cin>>a[i]>>b[i];
arr.push_back(a[i]);
arr.push_back(b[i]);
}
fo(i,1,k)
{
cin>>t[i];
arr.push_back(t[i]);
}
sort(arr.begin(),arr.end());
int m = arr.size();
fo(i,1,n)
{
a[i] = upper_bound(arr.begin(),arr.end(),a[i]) - arr.begin();
b[i] = upper_bound(arr.begin(),arr.end(),b[i]) - arr.begin();
}
fo(i,1,k)
{
t[i] = upper_bound(arr.begin(),arr.end(),t[i]) - arr.begin();
post[t[i]].push_back(i);
}
build(1,1,m);
ll ans = 0;
fo(i,1,n)
{
bool sw = 0;
if(a[i] > b[i])
swap(a[i], b[i]), sw = 1;
int pos = getmax(1,1,m,a[i],b[i]-1);
int num = getnum(1,1,m,b[i],m,pos);
if(pos > 0)
{
ans += arr[num & 1 ? a[i]-1 : b[i]-1];
//cout<<arr[num & 1 ? a[i]-1 : b[i]-1]<<'\n';
}
else
{
ans += arr[(num + sw) & 1 ? b[i]-1 : a[i]-1];
//cout<<arr[(num + sw) & 1 ? b[i]-1 : a[i]-1]<<'\n';
}
}
cout<<ans;
}
//25
//24
//12
//19
//20
//8
//14
//15
