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