#include<iostream> u

#include<iostream>
using namespace std;
int main(){
int n,a[1005],b,c=0;
cin>>n;
for(int i=1;i<=n;i++)cin>>a[i];
for(int i=1;i<=n;i++){
cin>>b;
c+=b*a[i];
}
cout<<c;
return 0;
}