#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define endl '\n'
#define MASK(i) (1LL << (i))
#define ull unsigned long long
#define ld long double
#define pb push_back
#define all(x) (x).begin() , (x).end()
#define BIT(x , i) ((x >> (i)) & 1)
#define TASK "task"
#define sz(s) (int) (s).size()
 
using namespace std;
const int mxN = 5e5 + 227;
const int inf = 1e9 + 277;
const int mod = 1e9 + 7;
const ll infll = 1e18 + 7;
const int base = 307;
const int LOG = 20;
 
template <typename T1, typename T2> bool minimize(T1 &a, T2 b) {
    if (a > b) {a = b; return true;} return false;
}
template <typename T1, typename T2> bool maximize(T1 &a, T2 b) {
    if (a < b) {a = b; return true;} return false;
}
 
int n;
int w[mxN];
pair<int, int> a[mxN];
int cnt[67][67];
int pre[67][67];
long long dp[67][67][67];
 
int getsum(int x, int y, int u, int v) {
    if(x > u) return 0;
    if(y > v) return 0;
    return pre[u][v] - pre[x - 1][v] - pre[u][y - 1] + pre[x - 1][y - 1];
}

void solve()
{
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i].fi >> a[i].se;
    for (int i = 1; i <= n; i++) cin >> w[i];

    memset(dp, -0x3f, sizeof(dp));

    for(int i = 1; i <= n; i++) cnt[a[i].fi][a[i].se]++;
    for(int i = 1; i <= n; i++)
    for(int j = 1; j <= n; j++) pre[i][j] = pre[i - 1][j] + pre[i][j - 1] - pre[i - 1][j - 1] + cnt[i][j];


    int res = 0;
    for (int len = 1; len <= n; len++) {
        for (int l = 1; l + len - 1 <= n; l++) {
            int r = l + len - 1;
            for (int k = 0; k <= n; k++) {
                if(len == 1) {  
                    if((k + cnt[l][r]) % l == 0) 
                        maximize(dp[l][r][k], 1LL * w[l] * (k + cnt[l][r]) / l);
                }
                else {
                    int tot = k + cnt[l][r];
                    for(int x = 0; x <= tot; x++) {
                        for(int mid = l; mid < r; mid++) {
                            if(x + getsum(l, mid + 1, l, r - 1) > n) continue;
                            if(tot - x + getsum(l + 1, r, mid, r) > n) continue;
                            if(dp[l][mid][x + getsum(l, mid + 1, l, r - 1)] == dp[0][0][0]) continue;
                            if(dp[mid + 1][r][tot - x + getsum(l + 1, r, mid, r)] == dp[0][0][0]) continue;
                            // if(l == 1 && r == 3) {
                            //     cout << l << ' ' << mid << ' ' << x << ' ' <<  getsum(l, mid + 1, l, r - 1) << ' ' << dp[l][mid][x + getsum(l, mid + 1, l, r - 1)] << endl;
                            //     cout << mid + 1 << ' ' << r << ' ' << tot - x << ' ' <<  getsum(l + 1, r, mid - 1, r) << ' ' << dp[mid + 1][r][tot - x + getsum(l + 1, r, mid - 1, r)] << endl;
                            //     cout << "Hi" << endl;
                            // }
                            maximize(dp[l][r][k], dp[l][mid][x + getsum(l, mid + 1, l, r - 1)] + dp[mid + 1][r][tot - x + getsum(l + 1, r, mid, r)]);
                        }
                    }
                }
            }
        }
    }


    if(dp[1][n][0] == dp[0][0][0]) cout << "impossible";
    else cout << dp[1][n][0];
}
 
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    // freopen(TASK".inp" , "r" , stdin);
    // freopen(TASK".out" , "w" , stdout);
 
    int tc = 1;
    //cin >> tc;
    while(tc--) {
        solve();
    }
    return 0;
}