#include <bits/stdc++.h>

const long long INF = 1E18;
int N;
std::pair<int, int> r[100];
int W[100];
std::map<std::pair<long long, int>, long long> dp;
std::set<std::pair<int, int>> available;
int pointer = 0;

long long search(long long flag, int hint) {
    if (hint == 0) return 0;
    auto it = dp.find({flag, hint});
    if (it != dp.end()) return it -> second;
    dp[{flag, hint}] = -INF;
    int op = pointer;
    while (pointer < N && r[pointer].second == hint) {
        available.insert({-r[pointer].first, pointer});
        ++pointer;
    }
    if (available.size() >= hint) {
        auto itt = available.begin();
        std::vector<int> storage;
        long long mod = 0;
        for (int i = 0; i < hint; ++i) {
            storage.push_back(itt -> second);
            mod ^= (1ll << itt -> second);
            auto nitt = itt;
            ++nitt;
            available.erase(itt);
            itt = nitt;
        }
        long long kk = search(flag ^ mod, hint);
        if (kk > -INF) dp[{flag, hint}] = std::max(dp[{flag, hint}], kk + W[hint]);
        for (int i = 0; i < hint; ++i) {
            available.insert({-r[storage[i]].first, storage[i]});
        }
    }
    if (available.empty() || -available.begin() -> first < hint) {
        dp[{flag, hint}] = std::max(dp[{flag, hint}], search(flag, hint - 1));
    }
    pointer = op;
    // printf("%lld %d %lld\n", flag, hint, dp[{flag, hint}]);
    return dp[{flag, hint}];
}

int main() {
    scanf("%d", &N);
    for (int i = 0; i < N; ++i) {
        scanf("%d%d", &r[i].first, &r[i].second);
    }
    for (int i = 1; i <= N; ++i) {
        scanf("%d", &W[i]);
    }
    std::sort(r, r + N, [&](auto &a, auto &b) { 
        return a.second > b.second;
    });
    long long ans = search(0, N);
    if (ans == -INF) {
        puts("impossible");
        return 0;
    }
    printf("%lld\n", ans);
}