#include<bits/stdc++.h>
using namespace std;
const int N=5e5+10;
typedef long long ll;
typedef pair<ll,ll> PII;
ll n,m,k;
ll a[N],b[N];
PII e[N];
int cnt=0;
ll ans=-1e18;
ll w[N];
vector<PII> v;

void dfs(int x,int sum,ll val){
    // cout<<x<<" "<<sum<<" "<<val<<endl;
	if(x==0){
		// cnt++;
        vector<int> vv;
        for(int i=v.size()-1;i>=0;i--){
            for(int j=1;j<=v[i].second;j++){
                vv.push_back(v[i].first);
            }
        }
        int j=1;
        for(int i=0;i<vv.size();i++){
            int k=1;
            while(k<=vv[i]){
                if(vv[i]>=e[j].first&&vv[i]<=e[j].second){
                    j++;
                    k++;
                }else return;
            }
        }
        ans=max(ans,val);
	}else{
        if(x==1){
            v.push_back({1,n-sum});
            dfs(x-1,n,val+(n-sum)*w[1]);
            v.pop_back();
            return;
        }
		for(int i=0;i<=n;i++){
			if(sum+i*x>n) break;
            v.push_back({x,i});
			dfs(x-1,sum+i*x,val+w[x]*i);
            v.pop_back();
        }
	}
}


int main(){
	cin>>n;
    for(int i=1;i<=n;i++){
        cin>>e[i].first>>e[i].second;
    }
    for(int i=1;i<=n;i++) cin>>w[i];
    sort(e+1,e+1+n);
	dfs(n,0,0);
    if(ans<-1e13) puts("impossible");
    else
    cout<<ans<<endl;
}