#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int INF = (int) 1e9 + 1e6 + 123;
const ll LINF = (ll) 1e18 + 1e9 + 123;
#define rep(i, s, t) for (auto i = (s); i < (t); ++(i))
#define per(i, s, t) for (auto i = (s); i >= (t); --(i))
#define sz(x) ((int)(x).size())
#define mp make_pair
#define pb push_back
#define all(x) (x).begin(), (x).end()
bool mini(auto &x, const auto &y) {
if (y < x) {
x = y;
return 1;
}
return 0;
}
bool maxi(auto &x, const auto &y) {
if (y > x) {
x = y;
return 1;
}
return 0;
}
void run();
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
run();
return 0;
}
const int N = (int) 2e5 + 123;
int n, k;
int a[N], b[N];
void run() {
cin >> n >> k;
rep(i, 0, n) {
cin >> a[i] >> b[i];
}
while (k--) {
int t;
cin >> t;
rep(i, 0, n) {
if (a[i] <= t) {
swap(a[i], b[i]);
}
}
}
ll ans = 0;
rep(i, 0, n) {
ans += a[i];
}
cout << ans << "\n";
}
