#include<bits/stdc++.h>
using namespace std;
int main() {
	int n,a[1001],s[1001],sum = 0;
	cin >> n;
	for (int i = 1 ;i <= n; i++) {
		cin >> a[i]; 
	}
	for (int i = 1;i <= n; i++) {
		cin >> s[i];
	}
	for (int i = 1;i <= n; i++) {
			sum += a[i] * s[i];
	}
	cout << sum;
	return 0;
}