#include <cstdio>
#include <algorithm>
using namespace std;

int n, i, j, k, nr, p[2002];

struct {
    int x, y;
} v[2002];

int main()
{
    freopen("trapez.in", "r", stdin);
    freopen("trapez.out", "w", stdout);
    scanf("%d", &n);
    for(i=1; i<=n; ++i)
        scanf("%d %d", &v[i].x, &v[i].y);

    for(i=1; i<=n-1; ++i)
        for(j=i+1; j<=n; ++j)
            if(v[i].x-v[j].x)
                p[++k]=(v[i].y-v[j].y)/(v[i].x-v[j].x);
            else
                p[++k]=0x3f3f3f3f;

    sort(p+1, p+k+1);
    for(i=1; i<=k-1; ++i)
        if(p[i]==p[i+1])
        {
            ++nr;
            while(p[i]==p[i+1])
                ++i;
            --i;
        }
    printf("%d\n", nr);
    return 0;
}