#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
//#define int long long
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,bmi,bmi2,lzcnt,popcnt")
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
const int mod = 1e9 + 7;
const int LOG = 20;
const int maxn = 1e5 + 5;
signed main() {
ios_base::sync_with_stdio(false);
cout.tie(0); cin.tie(0);
int n, q;
cin >> n >> q;
vector<int> a(n+1), b(n+1);
for(int i=1; i<=n; i++) cin >> a[i] >> b[i];
while(q--) {
int x;
cin >> x;
for(int i=1; i<=n; i++) if(a[i] <= x) swap(a[i], b[i]);
}
ll ans = 0;
for(int i=1; i<=n; i++) ans += a[i];
cout << ans << '\n';
return 0;
}
