#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];
int open[mxN];
int close[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];

    for(int i = 1; i <= n; i++) {
        open[a[i].fi]++;
        close[a[i].se + 1]++;
    }


    memset(dp, -0x3f, sizeof(dp));
    ll temp = dp[0][0][0];
    dp[0][0][0] = 0;

    for(int i = 0; i < n; i++)
    for(int j = 0; j <= n; j++)
    for(int k = 0; k <= n; k++) if(dp[i][j][k] != temp) {
        // cout << i << ' ' << j << ' ' << k << ' ' << dp[i][j][k] << endl;
        int newj = j + open[i + 1]; 
        int newk = k - close[i + 1];
        // if(i == 2 && j == 0 && k == 3) cout << newj << ' ' << newk << endl;
        if(newk < 0) continue;
        for(int x = 0; x * (i + 1) <= newj; x++) {
            maximize(dp[i + 1][newj - x * (i + 1)][newk + x * (i + 1)], dp[i][j][k] + w[i + 1] * x);
        }
    }

    ll res = temp;
    for(int i = 0; i <= n; i++) maximize(res, dp[n][0][i]);
    if(res == temp) cout << "impossible";
    else cout << res;
}
 
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;
}