#include <iostream>
using namespace std;
int N,cnt;
int main() {
cin >> N;
for(int x=N/3; x<=N/2; x++) {
for(int y=1; y<=x; y++) {
int z = N-x-y;
if(x>=y && y>=z && z>0 && x < y+z) {
cnt++;
}
}
}
cout<<cnt;
}