#pragma GCC optimize("Ofast,unroll-loops,no-stack-protector")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
using namespace std;
#define debug(s) cout<< #s <<" = "<< s <<endl
#define all(v) (v).begin(), (v).end()
#define KeepUnique(v) (v).erase( unique(all(v)), v.end() )
#define MEMSET(a,val) memset(a, val, sizeof a)
#define PB push_back
#define endl '\n'
typedef long long ll;
inline int myrand(int l, int r) {
int ret = rand(); ret <<= 15; ret ^= rand();
if(ret < 0) ret = -ret; ret %= (r-l+1); ret += l;
return ret;
}
template <typename F, typename S>
ostream& operator << (ostream& os, const pair< F, S>& p) {
return os<<"(" <<p.first<<", "<<p.second<<")"; }
typedef pair<int, int> ii;
template<typename T> using min_pq =
priority_queue<T, vector<T>, greater<T> >;
//int dx[] = {-1, +0, +1, +0};
//int dy[] = {+0, +1, +0, -1};
const int maxn = 200010;
const int inf = 2e9;
struct MaxSegTree {
vector<int> t;
MaxSegTree() {}
MaxSegTree(int N) {t.assign(N << 1, -1);}
void update(int p, int val) {
p += (t.size() >> 1);
t[p] = max(t[p], val);
for(; p > 1; p >>= 1) t[p >> 1] = max(t[p], t[p ^ 1]);
}
int query(int l, int r) {
r++;
int ret = -inf;
for(l += (t.size() >> 1), r += (t.size() >> 1); l < r; l >>= 1, r >>= 1) {
if(l & 1) ret = max(ret, t[l++]);
if(r & 1) ret = max(ret, t[--r]);
} return ret;
}
};
struct Tree {
vector<vector<int>> t;
Tree() {}
Tree(vector<int> &vec) {
t.resize(vec.size() << 2);
build(1, 0, vec.size() - 1, vec);
}
void build(int u, int b, int e, vector<int> &vec) {
for(int i = b; i <= e; i++) t[u].push_back(vec[i]);
sort(all(t[u]));
if(b == e) return;
int mid = b + e >> 1;
build(u << 1, b, mid, vec);
build(u << 1 | 1, mid + 1, e, vec);
}
int query(int u, int b, int e, int i, int j, int x) {
if(b > j or e < i) return 0;
if(i <= b and e <= j) return t[u].end() - lower_bound(all(t[u]), x);
int mid = b + e >> 1;
return query(u << 1, b, mid, i, j, x) + query(u << 1 | 1, mid + 1, e, i, j, x);
}
int query(int l, int r, int x) {
return query(1, 0, (t.size() >> 2) - 1, l, r, x);
}
};
int n, q;
vector<int> A, B, T;
vector<int> mp;
int flag[maxn];
int32_t main () {
// freopen("in", "r", stdin);
// input
cin >> n >> q;
A.resize(n), B.resize(n), T.resize(q);
for(int i = 0; i < n; i++) {
cin >> A[i] >> B[i];
if(A[i] > B[i]) swap(A[i], B[i]), flag[i] = 1;
}
for(int &b : T) cin >> b;
// end
// compress
for(int i = 0; i < n; i++) {
mp.push_back(A[i]);
mp.push_back(B[i]);
}
for(int b : T) mp.push_back(b);
sort(all(mp));
KeepUnique(mp);
for(int i = 0; i < n; i++) {
A[i] = lower_bound(all(mp), A[i]) - mp.begin();
B[i] = lower_bound(all(mp), B[i]) - mp.begin();
}
for(int &b : T) {
b = lower_bound(all(mp), b) - mp.begin();
}
// end
MaxSegTree ds(mp.size() + 10);
Tree tree(T);
for(int i = 0; i < q; i++) ds.update(T[i], i);
ll ans = 0;
for(int i = 0; i < n; i++) {
if(A[i] == B[i]) {
ans += mp[A[i]];
continue;
}
int it = ds.query(A[i], B[i] - 1) + 1, now;
if(!it) now = flag[i] ? B[i] : A[i];
else now = B[i];
int tog = tree.query(it, q - 1, B[i]);
if(tog & 1) now ^= A[i] ^ B[i];
ans += mp[now];
} cout << ans << endl;
}
