#include <bits/stdc++.h>
using namespace std;
int main()
{
	int n,ans;
	cin>>n;
	int a[n+1],b[n+1];
	for(int i=1;i<=n;i++)cin>>a[i];
	for(int i=1;i<=n;i++){
	    cin>>b[i];
        ans+=a[i]*b[i];}
	cout<<ans;
    return 0;
}