#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define MAXN 2510
// By flyfreemrn
inline ll read(){
	ll x=0,f=1;
	char c=getchar();
	while(c<'0'||c>'9'){
		if(c=='-')f=-1;
		c=getchar();
	}
	while(c>='0'&&c<='9'){
		x=x*10+c-'0';
		c=getchar();
	}
	return x*f;
}
inline void write(ll x){
	if(x>9)write(x/10);
	putchar(x%10+'0');
}
ll C[MAXN][MAXN],n,len,ans;
int main(){
	freopen("quad.in","r",stdin);
	freopen("quad.out","w",stdout);
//	C[0][0]=1;
//	for(int i=1;i<=2500;i++){
//		C[i][0]=1;
//		for(int j=1;j<=i;j++){
//			C[i][j]=C[i-1][j]+C[i-1][j-1];
//		}
//	}
	n=read();
	len=(n+1)/2;
	for(int i=1;i<=n;i++){
		for(int j=i+len-1;j<=n;j++){
			ll _len=j-i+1;
			if(i>1&&j<n){
				if(n-_len>2)ans+=n-_len-2;
			}else{
				if(n-_len>2)ans+=(n-_len-1)*(n-_len-2)/2;
			}
		}
	}
	cout<<(n-3)*(n-1)*(n-2)/6-ans;
	return 0;
}