#include<iostream> 
#include<cstring> 
#include<cstdio> 
#include<cmath> 
#include<algorithm>
using namespace std;
int main(){
	int arra[1010] = {};
	int arrb[1010] = {};
	int n;
	cin >> n;
	for(int i=0;i<n;i++){
		cin >> arra[i];
	}
	for(int i=0;i<n;i++){
		cin >> arrb[i];
	}
	int res=0;
	for(int i=0;i<n;i++){
		res = res+arra[i]*arrb[i];
	}
	cout << res;
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
int n,a[1010],b[1010],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];//计数器
	}
	cout<<sum<<endl;
	return 0;
}