#include <iostream>
using namespace std;
int main(){
int n,a[1000],b,sum=0;
cin >> n;
for(int i=0;i<n;i++){
cin >> a[i];
}
for(int i=0;i<n;i++){
cin >> b;
sum = sum + a[i] * b;
}
cout << sum << endl;
return 0;
}