#include <iostream>
#include <vector>
using namespace std;
vector<int> a , b;
int main(){
   int n , tmp;
   cin >> n;
   for(int i = 0; i < n; i++){
      cin >> tmp;
      a.push_back(tmp);
   }
   for(int i = 0; i < n; i++){
      cin >> tmp;
      b.push_back(tmp);
   }
   int ans = 0;
   for(int i = 0; i < n; i++){
      ans = ans + a[i] * b[i];
   }\
   cout << ans;

 


   




   return 0;
}