#include <cstdio>
#include <utility>
#include <algorithm>

typedef std::pair<int,int> Point;

const int MAX_N(1001);
const int MAX_VALUE(1 << 30);
const double GUARD(0.000001);

double v [MAX_N * MAX_N];
int n, end, Result;
Point p [MAX_N];

inline void Read (void)
{
	std::freopen("trapez.in","r",stdin);
	std::scanf("%d",&n);
	end = (n * (n - 1)) >> 1;
	for (int index(1) ; index <= n ; ++index)
		std::scanf("%d %d",&p[index].first,&p[index].second);
	std::fclose(stdin);
}

inline void Print (void)
{
	std::freopen("trapez.out","w",stdout);
	std::printf("%d\n",Result);
	std::fclose(stdout);
}

inline void Compute (void)
{
	int i, j, index(1);
	for (i = 1 ; i <= n ; ++i)
		for (j = i + 1 ; j <= n ; ++j)
		{
			v[index] = static_cast<double>(p[j].second - p[i].second) / (p[j].first - p[i].first);
			++index;
		}
	std::sort(v + 1,v + end + 1);
	i = 1;
	while (i <= end)
	{
		for (j = i + 1 ; j <= end && v[j] >= v[i] - GUARD && v[j] <= v[i] + GUARD ; ++j)
			/* do nothing */;
		Result += ((j - i) * (j - i - 1)) >> 1;
		i = j;
	}
}

int main (void)
{
	Read();
	Compute();
	Print();
	return 0;
}