#include<cstdio>
#include<iostream>
#define int long long
using namespace std;
int n;
signed main(){
    freopen("TricountUVa.in","r",stdin);
    freopen("TricountUVa.out","w",stdout);
    while(scanf("%lld",&n)==1){
        if(n<3)return 0;
        int ans=0;
        for(int i=2;i<=n-2;i++){
            if(n-2*i+1>0){
                ans+=(n-2*i+1)*(i-1);
            }
            int st=max(n-i+2,i+1);
            ans+=(n-st+1)*(n-st)/2;
        }
        printf("%lld\n",ans);
    }
    return 0;
}