#include<iostream>
#include<algorithm>
#include<stack>
#include<set>
#include<unordered_set>
#include<queue>
#include<deque>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<map>
#include<string>
#include<vector>
#include<array>
#include<functional>
using namespace std;
typedef long long ll;
ll highbit(ll x){
    ll ans=2;
    int num=1;
    while(x){
        x>>=2;
        ans<<=2;
        num++;
    }
    return num;
}
ll lowbit(ll x){
    return x&(-x);
}
long long max(long long a,long long b){
    return a>b?a:b;
}
long long min(long long a,long long b){
    return a>b?b:a;
}
ll gcd(ll x,ll y)
{
    if(y==1)
        return x;
    return gcd(y,x%y);
}
const int maxn=100;
ll w[maxn];
ll L[maxn];
ll R[maxn];
ll ans=-1e17;
ll mx=0;
array<ll,61> num;
array<ll,61> diff;
bool flag=0;
struct node{
    ll w,num;
    ll id;
    bool operator<(node& that){
        return this->w*that.num>this->num*that.w;
    }
};
void dfs(array<ll,61>& num,array<ll,61>& diff,int pos,int n){
    if(pos==n+1){
        ll buff=0;
        for(int i=1;i<=n;i++){
            if(num[i]%i!=0){
                return;
            }
        }
        flag=true;
        for(int i=1;i<=n;i++){
            buff+=w[i]*(num[i]/i);
        }
        ans=max(ans,buff);
        return;
    }
    vector<node> buff1;
    for(int i=1;i<=n;i++){
        if((num[i]%i)==0){
            if(diff[i]>=(i-(num[i]%i))){
                node now;
                now.num=i;
                now.w=w[i];
                buff1.push_back(now);
            }
            continue;
        }
        if(diff[i]<(i-(num[i]%i))){
            return;
        }else{
            node now;
            now.num=i;
            now.w=w[i];
            buff1.push_back(now);            
        }
    }
    if(buff1.size()==0){
        return;
    }
    sort(buff1.begin(),buff1.end());
    ll sum=0;
    int nn=n;
    for(int i=1;i<=n;i++){
        sum+=w[i]*(num[i]/i);
        nn-=(num[i]/i);
    }
    for(int i=1;i<=n;i++){
        if((num[i]%i)==0){
          continue;
        }
        nn-=(i-(num[i]%i));
        sum+=w[i];
    }
    mx=(buff1[0].w/buff1[0].num);
    mx++;
    if(nn<0){
        return;
    }else{
        sum+=(mx*nn);
        if(sum<=ans){
            return;
        }
    }
    vector<node> buff;
    for(int i=L[pos];i<=R[pos];i++){
        ll nk=i-(num[i]%i);
        node now;
        now.id=i;
        now.num=nk;
        now.w=w[i];
        buff.push_back(now);
    }
    sort(buff.begin(),buff.end());
    for(auto q:buff){
        int i=q.id;
        if(diff[i]>=(i-(num[i]%i))){
            for(int j=L[pos];j<=R[pos];j++){
                diff[j]--;
            }
            num[i]++;
            dfs(num,diff,pos+1,n);
            num[i]--;
            for(int j=L[pos];j<=R[pos];j++){
                diff[j]++;
            }
        }
    }
    return ;
}
void solve() {
    int n;
    cin>>n;
    for(int i=1;i<=n;i++){
        diff[i]=num[i]=0;
    }
    for(int i=1;i<=n;i++){
        cin>>L[i]>>R[i];
        for(int j=L[i];j<=R[i];j++){
            diff[j]++;
        }
    }
    for(int i=1;i<=n;i++){
        cin>>w[i];
    }
    dfs(num,diff,1,n);
    if(!flag){
        cout<<"impossible"<<endl;
    }else{
        cout<<ans<<endl;
    }
    return;
}
int main(void){
    unsigned int t;
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    //freopen("input.in","r",stdin);
    //cin>>t;
    t=1;
    while(t--){
        solve();
    }
    return 0;
}