#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
const int MaxN = 2e5 + 5;
const int MaxLog = 19;
int n, q;
pair<long long, long long> arr[MaxN];
pair<long long, int> query[MaxN];
void Inp()
{
cin >> n >> q;
for (int x = 1; x <= n; x++)
{
cin >> arr[x].first >> arr[x].second;
}
for (int x = 1; x <= q; x++)
{
cin >> query[x].first;
query[x].second = x;
}
sort(query + 1, query + q + 1);
}
int Sparse[MaxLog][MaxN];
void Build()
{
for (int x = 1; x <= q; x++)
{
Sparse[0][x] = query[x].second;
}
for (int x = 1; x < MaxLog; x++)
{
for (int y = 1; y + (1 << x) - 1 <= q; y++)
{
Sparse[x][y] = max(Sparse[x - 1][y], Sparse[x - 1][y + (1 << (x - 1))]);
}
}
}
int Get(int l, int r)
{
if (r < l)
{
return 0;
}
int p = __lg(r - l + 1);
return max(Sparse[p][l], Sparse[p][r - (1 << p) + 1]);
}
int Fenwick[MaxN];
void Update(int u)
{
int idx = u;
while (idx <= q)
{
Fenwick[idx]++;
idx += (idx & (-idx));
}
}
int Query(int u)
{
int idx = u, res = 0;
while (idx > 0)
{
res += Fenwick[idx];
idx -= (idx & (-idx));
}
return res;
}
vector<int> add[MaxN];
void Exc()
{
Build();
for (int x = 1; x <= n; x++)
{
int l = 1, r = q, mid, res = q + 1;
while (l <= r)
{
mid = (l + r) / 2;
if (query[mid].first >= max(arr[x].first, arr[x].second))
{
res = mid;
r = mid - 1;
}
else
{
l = mid + 1;
}
}
add[res].push_back(x);
}
long long ans = 0;
for (int w = q + 1; w > 0; w--)
{
if (w <= q)
{
Update(query[w].second);
}
for (int x : add[w])
{
int l = 1, r = q, mid, res = q + 1;
while (l <= r)
{
mid = (l + r) / 2;
if (min(arr[x].first, arr[x].second) <= query[mid].first)
{
res = mid;
r = mid - 1;
}
else
{
l = mid + 1;
}
}
int k = Get(res, w - 1), p = Query(q) - Query(k);
if (k != 0)
{
if (p & 1)
{
ans += min(arr[x].first, arr[x].second);
}
else
{
ans += max(arr[x].first, arr[x].second);
}
}
else
{
if (p & 1)
{
ans += arr[x].second;
}
else
{
ans += arr[x].first;
}
}
//cout << x << " " << w << " " << res << " " << k << " " << p << " " << ans << "\n";
}
}
cout << ans;
}
int main()
{
//freopen("A.INP", "r", stdin);
//freopen("A.OUT", "w", stdout);
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int test = 1;
//cin >> test;
for (int w = 1; w <= test; w++)
{
Inp();
Exc();
}
return 0;
}
