#include <bits/stdc++.h>
using namespace std;
#define int long long
#define vi vector<int>
#define ff first
#define ss second
#define pb push_back
#define all(a) (a).begin(),(a).end()
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
const int mod = 1e9 + 7;
signed main() {
int n;
cin >> n;
int x;
vector<int> a(n);
vector<int> b(n);
for (int i = 0; i < n; i++) {
cin >> a[i];
x = a[i];
}
for (int i = 0; i < n; i++) {
cin >> b[i];
}
if(n<3) {
cout<<"0";
return 0;
}
cout << (n - 2) * x;
return 0;
}
