#include <bits/stdc++.h>

using namespace std;

int main() { int a[10000], b[10000], n, m = 0;

cin >> n;

for (int i = 0; i < n; i++) {

	cin >> a[i] ;

}
for (int i = 0; i < n; i++) {

	cin  >> b[i];

}
for (int i = 0; i < n; i++) {


	m = m + a[i] * b[i];
}
cout << m << endl;
return 0;

}