#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
#include <cmath>

using namespace std;

const int MAXN=600;

int n,i,j,k,ans;
double x[MAXN],y[MAXN],a,b,c;

inline double cha(int p1,int p2)
{
	return x[p1]*y[p2]-x[p2]*y[p1];
}

int main()
{
	freopen("triecount.in","r",stdin);
	freopen("triecount.out","w",stdout);
	scanf("%d",&n);
	for (i=1;i<=n;i++)
		scanf("%lf%lf",&x[i],&y[i]);
	if (n>=MAXN)
	{
		printf("0\n");
		return 0;
	}
	ans=0;
	for (i=1;i<=n-2;i++)
		for (j=i+1;j<=n-1;j++)
			for (k=j+1;k<=n;k++)
			{
				a=cha(i,j);
				b=cha(j,k);
				c=cha(k,i);
				if (a<0 && b<0 && c<0) ++ans;
				if (a>0 && b>0 && c>0) ++ans;
			}
	printf("%d\n",ans);
	return 0;
}