#include<bits/stdc++.h>
using namespace std;

long long n,ans=0;

int main()
{
    freopen("TricountUVa.in","r",stdin);
    freopen("TricountUVa.out","w",stdout);
    while(1)
    {
        ans=0;
        cin>>n;
        if(n<3) break;
        for(long long i=1;i<=n;++i)
        {
            for(long long j=i+1;j<=n;++j)
            {
                for(long long k=j+1;k<=n;++k)
                {
                    if(i+j>k) ans++;
                }
            }
         } 
        cout<<ans<<endl;
    }
    return 0;
}