#include <bits/stdc++.h>
#define xs(a) cout<<setiosflags(ios::fixed)<<setprecision(a);
#define endl '\n'
using namespace std;
using ll = long long;
const int N=1e6+5;
#define int long long

array<int,2>a[N];
int w[N];
int n, res=-1e18;
int vis[N];
void dfs(int u, int ans){
    if(u == n+1){
        for(int i=1; i<=n; i++)if(!vis[i])return ;
        res = max(res, ans);
        return ;
    }
    dfs(u+1, ans);
    int cnt = 0;
    vector<int>v;
    for(int i=1; i<=n && cnt <= u; i++)if(!vis[i]){
        if(a[i][0] <= u && a[i][1] >= u ){
            cnt ++;
            v.push_back(i);
        }
    }
    if(cnt == u){
        for(auto x: v)vis[x] = 1;
        dfs(u, ans + w[u]);
        for(auto x: v)vis[x] = 0;
    }
}

signed main(){
	cin.tie(0)->sync_with_stdio(0);
    cin >> n;
    for(int i=1; i<=n; i++) cin >> a[i][0] >> a[i][1];
    sort(a+1, a+1+n);
    for(int i=1; i<=n; i++) cin >> w[i];
    dfs(1, 0);
    if(res == -1e18) cout << "impossible" << endl;
    else cout << res << endl;
	return 0;
}