#include<bits/stdc++.h>
using namespace std;
int main(){
    long long n,a[1010],b[1010],s=0;
    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>a[i];
    for(int i=1;i<=n;i++){
        cin>>b[i];
        s+=a[i]*b[i];
    }
    cout<<s;
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
#define mem(a, b) memset(a, b, sizeof(a))
#define rep(i, a, b) for (int i = a; i <= b; ++i)
#define rrep(i, a, b) for (int i = a; i >= b; --i)
#define FOR(i, a, b) for (int i = a; i < b; ++i)
#define pb push_back
#define MP make_pair
#define all(v) v.begin(), v.end()
#define clr(v) v.clear()
#define isEven(x) !(x & 1)
#define yes cout<<"YES"<<endl
#define no cout<<"NO"<<endl
int main() {
	ios::sync_with_stdio ( false );
	cin.tie ( 0 );
	int n, ans = 0;
	cin >> n;
	vector<int>a ( n );
	vector<int>b ( n );
	rep ( i, 1, n ) cin >> a[i];
	rep ( i, 1, n ) cin >> b[i];
	rep ( i, 1, n ) ans = ans + a[i] * b[i];
	cout << ans;
	return 0;
}