#include <bits/stdc++.h>

using namespace std;

#define int long long

const int N = 60 + 10;
int n;
struct Student {
  int l, r;
  friend istream& operator >> (istream& is, auto& rhs) { 
    return is >> rhs.l >> rhs.r;
  }
} s[N];
int w[N];

int f[1 << 20];
int value[1 << 20];

int32_t main() { 
  cin.tie(0)->sync_with_stdio(0);

  cin >> n;
  for (int i = 1; i <= n; ++i) cin >> s[i];
  for (int i = 1; i <= n; ++i) cin >> w[i];

  memset(value, -15, sizeof value);
  for (int mask = 1; mask < (1ll << n); ++mask) { 
    int l = 1, r = n;
    for (int i = 1; i <= n; ++i) { 
      if (!(mask >> i - 1 & 1)) continue;
      l = max(l, s[i].l);
      r = min(r, s[i].r);
    }
    
    int cnt = __builtin_popcount(mask);
    for (int j = l; j <= r; ++j)
      if (!(cnt % j)) value[mask] = max(value[mask], cnt / j * w[j]);
  }
  
  memset(f, -15, sizeof f);
  f[0] = 0;
  for (int mask = 1; mask < (1ll << n); ++mask) { 
    auto& ret = f[mask];
    for (int submask = mask; submask; submask = submask - 1 & mask)
      ret = max(ret, f[mask ^ submask] + value[submask]);
  }

  if (f[(1ll << n) - 1] <= -1'000'000'000'000'000'000) cout << "impossible\n";
  else cout << f[(1ll << n) - 1] << "\n";
}