using namespace std;
#include<cstdio>
#include<algorithm>
#define Nm 1500
#define eps 1e-3
#define sin60 0.866025403784438
#define f first
#define s second
#define abs(a) ((a)<0?-(a):(a))
int n,ans;
pair<double,double> P[Nm];

void read()
{
    int i;

    freopen("triang.in","r",stdin);
    scanf("%d",&n);
    for(i=0;i<n;++i)
        scanf("%lf%lf",&P[i].f,&P[i].s);
}

bool bs(double x, double y)
{
    int l=0,r=n-1,m;

    while(l<=r)
    {
        m=l+r>>1;
        if(abs(x-P[m].f)<eps && abs(y-P[m].s)<eps) return 1;
        if(x<=P[m].f-eps || abs(x-P[m].f)<eps && y<=P[m].s-eps) r=m-1;
        else l=m+1;
    }
    return 0;
}

bool cmp(pair<double,double> a, pair<double,double> b)
{
    return a.f<=b.f-eps || abs(a.f-b.f)<eps && a.s<=b.s-eps;
}

void solve()
{
    int i,j;
    double x,y;

    sort(P,P+n,cmp);

    for(i=0;i<n;++i)
        for(j=i+1;j<n;++j)
        {
            x=P[j].f-P[i].f;
            y=P[j].s-P[i].s;
            ans+=bs(x*0.5-y*sin60+P[i].f,y*0.5+x*sin60+P[i].s);
            ans+=bs(x*0.5+y*sin60+P[i].f,y*0.5-x*sin60+P[i].s);
        }
}

void write()
{
    freopen("triang.out","w",stdout);
    printf("%d\n",ans/3);
}

int main()
{
    read();
    solve();
    write();
    return 0;
}