#include<cstdio>
#include<cmath>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<queue>
using namespace std;
const int maxn=3e6+10;
const int mod=1e9+7;
long long read(){
	long long ans=0,f=1;
	char c=getchar();
	while(c<'0'||c>'9'){
		if(c=='-') f=-1;
	 	c=getchar();
	}
	while(c>='0'&&c<='9'){
	 	ans=ans*10+c-'0';
	 	c=getchar();
	}
	return ans*f;
}
long long n,m,z,t;
struct noe{
	int l,r;
}h[maxn];
long long c[maxn];
bool cmp(noe a,noe b){
	return a.r<b.r;
}
int fl=0,zhan[maxn],top=0;
long long ans=-1e9;
struct node{
	int l,r;
	bool operator <(const node &a)const{
		return l>a.l;
	}
};
priority_queue<node>q;
struct nde{
	int l,r;
	bool operator <(const nde &a)const{
		return r<a.r;
	}
};
priority_queue<nde>qq;
void check(int x,int y){
	if(!x){
		while(!q.empty()) q.pop();
		while(!qq.empty()) qq.pop();
		for(int i=1;i<=n;i++){
			nde tmp;
			tmp.l=h[i].l;
			tmp.r=h[i].r;
			qq.push(tmp);
		}
		long long sum=0;
		for(int i=1;i<=top;i++){
			int sm=zhan[i];
			while(!qq.empty()&&qq.top().r>=zhan[i]){
				nde tmp=qq.top();
				qq.pop();
				node pmt;
				pmt.l=tmp.l;
				pmt.r=tmp.r;
				q.push(pmt);
				sm--;
			}
			//printf("*%d %d",sm,i);
			if(sm>0) return;
		//	printf("==%d\n",i);
			while(sm<0){
				sm++;
				node pmt=q.top();
				q.pop();
				nde tmp;
				tmp.l=pmt.l;
				tmp.r=pmt.r;
				qq.push(tmp);
			}
			//printf("%d %d %d\n",q.top().l,q.top().r,zhan[i]);
			while(!q.empty()){
				node pmt=q.top();
				q.pop();
				if(pmt.l>zhan[i]) return;
			}
			sum+=c[zhan[i]];
		}
		ans=max(ans,sum);
		fl=1;
		return;
	}
	for(int j=min(y,x);j>=1;j--){
		zhan[++top]=j;
		check(x-j,j);
		top--;
	}
}
int main(){
	n=read();
	for(int i=1;i<=n;i++){
		h[i].l=read();
		h[i].r=read();
	}
	for(int i=1;i<=n;i++) scanf(" %lld",&c[i]);
	check(n,n);
	if(fl) printf("%lld",ans);
	else printf("impossible");
	return 0;
}