#include <bits/stdc++.h>

using i64 = long long;

const int N = 65;

int n;
struct Student {
	int l, r;
	bool operator < (const Student & x) const {
		return l < x.l;
	}
}a[N];

int w[N], p[N];
int ans = -1E9;
void dfs(int sum, int now, int cnt) {
	if (!sum) {
		int res = 0;
		for (int i = 1; i <= cnt; i++) {
			res += w[p[i]];
		}

		if (res <= ans) {
			return;
		}

		std::multiset<int> s;
		for (int i = 1, j = 1; i <= cnt; i++) {
			while (j <= n && a[j].l <= p[i]) {
				s.insert(a[j].r), ++j;
			}

			for (int k = 1; k <= p[i]; k++) {
				auto it = s.lower_bound(p[i]);

				if (it == s.end()) {
					return;
				}

				s.erase(it);
			}
		}

		ans = res;
		return;
	}

	for (int i = now; i <= sum; i++) {
		p[cnt + 1] = i;
		dfs(sum - i, i, cnt + 1);
	}
}

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);

	std::cin >> n;

	for (int i = 1; i <= n; i++) {
		std::cin >> a[i].l >> a[i].r;
	}

	for (int i = 1; i <= n; i++) {
		std::cin >> w[i];
	}

	std::sort(a + 1, a + n + 1);

	dfs(n, 1, 0);

	if (ans == -1E9) {
		std::cout << "impossible";
	} else {
		std::cout << ans;
	}
	return 0;
}