#include <bits/stdc++.h>
using namespace std;
int i,sum;
int main(){
	cin>>i;
	for(int j=1;j<=i/3;j++){
		for(int k=j;k<=(i-j)/2;k++){
			if(i-k-j<j+k&&(k!=j||j!=i-k-j)){
				sum++;
			}
		}
	}
	cout<<sum;
	return 0;
}

/**************************************************************
	Problem: 1079
	User: zhouhongyi
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/