#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define endl "\n"
#define INF 1000000000
#define LINF 10000000000000000LL
#define pb push_back
#define all(x) x.begin(), x.end()
#define len(s) (int)s.size()
#define test_case { int t; cin>>t; while(t--)solve(); }
#define single_case solve();
#define line cerr<<"----------"<<endl;
#define ios { ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); cerr.tie(NULL); }
#define mod 1000000007LL
const int N = 2e5 + 50;
int a[N], b[N], n;
int main()
{
ios
cin>>n;
int k;
cin>>k;
for(int i = 0;i<n;i++) cin>>a[i]>>b[i];
while(k--)
{
int x;
cin>>x;
for(int i = 0;i<n;i++) if(a[i]<=x) swap(a[i], b[i]);
}
ll ans = 0;
for(int i = 0;i<n;++i) ans += (ll)a[i];
cout<<ans;
return 0;
}
