#define _CRT_SECURE_NO_WARNINGS
#include<map>
#include<queue>
#include<vector>
#include<fstream>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<unordered_map>
using namespace std;

const int N=70;
typedef long long ll;
int n;
ll ans,w[N];
vector<int>c;
priority_queue<int,vector<int>,greater<int> >q;

struct Node{
	int l,r;
	inline bool operator<(const Node that){
		return l==that.l?r<that.r:l<that.l;
	}
}a[N];

inline bool valid()
{
	while(q.size())q.pop();
	int pos=0; 
	for(auto x:c)
	{
		while(pos+1<=n&&a[pos+1].l<=x)
			q.push(a[++pos].r);
		while(q.size()&&q.top()<x)q.pop();
		if(q.size()<x)return 0;
		for(int i=1;i<=x;i++)
			q.pop();
	}
	return 1;
}


inline void dfs(int pos,int lst)
{
	if(!pos)
	{
		//for(auto x:c)
		//	cout<<x<<" ";
		//cout<<endl;
		if(valid())
		{
			ll posans=0;
			for(auto x:c)
				posans+=w[x];
			ans=max(ans,posans);
		}
		return;
	}
	if(pos<lst)return;
	for(int i=lst;;i++)
	{
		if((pos-i)&&pos-i<i)break;
		c.push_back(i);
		dfs(pos-i,i);
		c.pop_back();
	}
}
	

signed main()
{
	ans=-1000000000000000000ll;
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
		scanf("%d%d",&a[i].l,&a[i].r);
	for(int i=1;i<=n;i++)
		scanf("%lld",&w[i]);
	sort(a+1,a+1+n);
	dfs(n,1);
	c.clear();
	c.push_back(n);
	if(valid())ans=max(ans,w[n]);
	if(ans==-1000000000000000000ll)
		puts("impossible");
	else printf("%lld\n",ans);
	return 0;
}