#include <bits/stdc++.h>
using namespace std;
using ll = long long;
struct SegTree {
int n;
vector<int> st;
SegTree(int _n=0){ init(_n); }
void init(int _n){
n = 1; while(n < _n) n <<= 1;
st.assign(2*n, 0);
}
void build(const vector<int>& a){
int m = (int)a.size();
init(m);
for(int i=0;i<m;i++) st[n+i] = a[i];
for(int i=n-1;i>0;i--) st[i] = max(st[2*i], st[2*i+1]);
}
int query(int l, int r){
if(l>r) return 0;
l += n; r += n;
int res = 0;
while(l <= r){
if(l&1) res = max(res, st[l++]);
if(!(r&1)) res = max(res, st[r--]);
l >>= 1; r >>= 1;
}
return res;
}
};
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m;
if(!(cin >> n >> m)) return 0;
vector<int> A(n), B(n);
for(int i=0;i<n;i++) cin >> A[i] >> B[i];
vector<int> T(m);
for(int j=0;j<m;j++) cin >> T[j];
vector<int> vals;
vals.reserve(n*2 + m);
for(int x: A) vals.push_back(x);
for(int x: B) vals.push_back(x);
for(int x: T) vals.push_back(x);
sort(vals.begin(), vals.end());
vals.erase(unique(vals.begin(), vals.end()), vals.end());
auto idx = [&](int x){
return int(lower_bound(vals.begin(), vals.end(), x) - vals.begin());
};
int V = (int)vals.size();
vector<int> last(V, 0);
for(int j=0;j<m;j++){
int p = idx(T[j]);
last[p] = j+1;
}
SegTree seg;
seg.build(last);
ll ans = 0;
for(int i=0;i<n;i++){
int cur = A[i], other = B[i];
int prev = 0;
while(true){
if(cur == other) break;
int low = min(cur, other);
int high = max(cur, other);
int l = int(lower_bound(vals.begin(), vals.end(), low) - vals.begin());
int r = int(lower_bound(vals.begin(), vals.end(), high) - vals.begin()) - 1;
if(l > r){
break;
}
int mx = seg.query(l, r);
if(mx <= prev) break;
prev = mx;
swap(cur, other);
}
ans += cur;
}
cout << ans << "\n";
return 0;
}
