include

include

include

using namespace std;
int main()
{
int n,pos[301],delta[301];
long long int possession=0,debt=0,ans=0;
cin>>n;
for(int i=0;i<n;i++)
cin>>pos[i];
for(int i=0;i<n;i++)
cin>>delta[i];
ans=pos[n-1];
int j=0;
for(int i=0;i<n;i++)
{
if(delta[i]>=0)
{
possession+=delta[i];
if(debt<=possession&&debt!=0)
{
possession-=debt;
debt=0;
if(i!=j)
ans=ans+2(pos[i]-pos[j]);
}
}
else
{
if(debt==0) j=i;
debt-=delta[i];
if(debt<=possession)
{
possession-=debt;
debt=0;
if(i!=j)
ans=ans+2(pos[i]-pos[j]);
}
}
}
cout<<ans;
return 0;
}