#include <bits/stdc++.h>

using ll = long long;

using namespace std;


void solve() {
    int n;
    n = 60;
    cin >> n;
    vector<vector<int>> tt(n + 1);
    vector<int> w(n + 1);
    for (int i = 1; i <= n; i++) {
        int l, r;
        l = 1, r = n;
        cin >> l >> r;
        tt[l].push_back(r);        
    }
    for (int i = 1; i <= n; i++) {
        w[i] = 0;
        cin >> w[i];
    }
    vector<int> q(n + 2);
    int ans = -1e9;
    auto dfs = [&](auto self, int sum, int now, int res) {
        if (sum == 0) {
            ans = max(ans, res);
            return;
        }
        if (now == n + 1 || sum < now) return ;
        vector<int> rq = q;
        for (auto o : tt[now]) q[o]++;
        self(self, sum, now + 1, res);
        int ttt = now;
        // cout << now << '\n';
        // for (auto cnt : q) cout << cnt << ' ';
        // cout << '\n'; 
        for (int t = 1; t * now <= sum; t++) {
            res += w[now];
            for (int j = 1; j <= now; j++) {
                while(ttt <= n && !q[ttt]) ttt++;
                q[ttt]--;
            }
            // cout << now << ' ' << t << ' ' << ttt << ' ' << res << '\n';
            if (ttt > n) {
                break;
            }
            if (sum == t * now || sum - t * now >= now + 1) {
                self(self, sum - t * now, now + 1, res);
            }
            res -= w[now];
        }
        q = rq;
    };
    // for (auto o : tt[1]) q[o]++;
    dfs(dfs, n, 1, 0);
    if (ans <= -1e9) {
        cout << "Impossible\n";
    } else {
        cout << ans << '\n';
    }
    cerr << 1. * clock() / CLOCKS_PER_SEC << '\n';
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    int t = 1;
    // cin >> t;
    while(t--) solve();
    return 0;
}