#include <bits/stdc++.h>
#define INF (1e9)
const double eps = (1e-14);
using namespace std;
class POINT
{
private:
    int x,y;
public:
    POINT()
    {
        x=0;
        y=0;
    };
    POINT(int _x,int _y)
    {
        x=_x;
        y=_y;
    };
    POINT(const POINT &other)
    {
        x=other.x;
        y=other.y;
    };
    void set(int x1,int y1)
    {
        x=x1;
        y=y1;
    }
    double dist (const POINT &other)
    {
        return sqrt((x-other.x)*(x-other.x)+(y-other.y)*(y-other.y));
    }
    bool operator == (const POINT &other)
    {
        return (fabs(x-other.x)<eps&&fabs(y-other.y)<eps);
    }
    bool operator != (const POINT &other)
    {
        return !(fabs(x-other.x)<eps&&fabs(y-other.y)<eps);
    }
    double panta (const POINT &other)
    {
        if(fabs(x-other.x)<eps)
            return INF;
        return 1.0*(y-other.y)/(x-other.x);
    }
    
};
POINT v[1005];
double ddiisstt[1005*1005];
int main()
{
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    int n,k=0;
    scanf("%d",&n);
    for(int i=1;i<=n;++i)
    {
        int xx,yy;
        scanf("%d %d",&xx,&yy);
        v[i].set(xx,yy);
    }
    for(int i=1;i<=n;++i)
    {
        for(int j=i+1;j<=n;++j)
        {
            ddiisstt[++k]=v[i].panta(v[j]);
        }
    }
    sort(ddiisstt+1,ddiisstt+k+1);
    int sum=0;
    int cnt=0;
    for(int i=1;i<=k;++i)
    {
        cnt=0;
        while(fabs(ddiisstt[i]-ddiisstt[i-1])<eps)
        {
            cnt++;
            i++;
        }
        sum+=((cnt+1)*cnt)/2;
    }
    sum+=((cnt+1)*cnt)/2;
    printf("%d",sum);
    return 0;
}