//#include "bits/stdc++.h"

#define _USE_MATH_DEFINES
#include<cstdio>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <deque>
#include <algorithm>
#include <functional>
#include <iostream>
#include <list>
#include <map>
#include <array>
#include <unordered_map>
#include<unordered_set>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#include <iterator>
#include<iomanip>
#include<complex>
#include<fstream>
#include<assert.h>

#include<stdio.h>

using namespace std;

#define rep(i,a,b) for(int i=(a), i##_len=(b);i<i##_len;i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(c) begin(c),end(c)

#define int ll
#define SZ(x) ((int)(x).size())
#define pb push_back
#define mp make_pair

//typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ll, int> pli;
typedef pair<int, double> pid;
typedef pair<double, int> pdi;
typedef pair<double, double> pdd;
typedef vector< vector<int> > mat;

template<class T> bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, const T &b) { if (b < a) { a = b; return true; } return false; }

const int INF = sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)1e9 + 7;

const double EPS = 1e-9;

signed main()
{
	cin.tie(0);
	ios::sync_with_stdio(false);

	int N;
	cin >> N;

	int ans = 0;

	vector<pii> P(N);
	rep(i, 0, N)
	{
		cin >> P[i].first >> P[i].second;
	}

	rep(i, 0, N)rep(j, i + 1, N)
	{
		int dx = P[j].first - P[i].first;
		int dy = P[j].second - P[i].second;

		if (dx < 0)
		{
			dx *= -1;
			dy *= -1;
		}

		if (-dx <= dy && dy <= dx)
		{
			ans++;
		}
	}

	cout << ans << endl;

	return 0;
}
#include<bits/stdc++.h>

using namespace std;

#define int long long int
int fun(int a)
{
	int ret=0;
	while(a>0)
	{
		ret+=a%10;
		a=a/10;
	}
	return ret
;}

main()
{

int n;
cin>>n;
float x[n],y[n];
for(int i=0;i<n;i++)
{
	cin>>x[i]>>y[i];
}
int cou=0;
for(int i=0;i<n;i++)
{
	for(int j=i+1;j<n;j++)
	{
		float num=(y[i]-y[j])/(x[i]-x[j]);
		if(num<=1&&num>=-1)
		{
			cou++;
		}
	}
}
cout<<cou<<endl;
}