#include <bits/stdc++.h>
using namespace std;
int n;
int l, r;
long long ans;
int main(){
    freopen("TricountUVa.in", "r", stdin);
    freopen("TricountUVa.out", "w", stdout); 
    while(1){
        cin >> n;
        ans = 0;
        if(n < 3){
            return 0;
        }
        for(int i = 2;i <= n - 2;i++){
            l = i + 2;
            r = n - i + 2;
            if(r >= l){
                ans += (r - l + 1) * (i - 1);
                ans += (i - 2) * (i - 1) / 2;
            }
            else{
                int a = n - l + 1;
                ans += (a + 1) * a / 2;
            }
        }
        cout<<ans<<endl;
    } 
    return 0;
}