#include<iostream>
#include<ostream>
using namespace std;
int a[3000000],b[3000000],n,sum;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++) cin>>a[i];
	for(int i=1;i<=n;i++){
		cin>>b[i];
		sum+=a[i]*b[i];
	}
    cout<<sum;
}