#include <bits/stdc++.h>
using namespace std;
int main(){
	int i,n;
    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)){
                n++;
            }
        }
    }
    cout<<n;
}
/**************************************************************
	Problem: 1079
	User: yangjunwen
	Language: C++
	Result: Wrong Answer
****************************************************************/