#include <bits/stdc++.h> using namespace std;

int main() { int n, s = 0; int a[100005]; int b[100005]; cin >> n; for (int i = 1; i <= n; i++) { cin >> a[i]; } for (int i = 1; i <= n; i++) { cin >> b[i]; } for (int i = 1; i <= n; i++) { s = s + a[i] * b[i]; }

cout << s;
return 0;

}