#include <bits/stdc++.h>
#define SELECTER(_1,_2,_3,SELECT,...) SELECT
#define rep1(i,n) for(int i=0;i<(int)n;++i)
#define rep2(i,a,n) for(int i=(int)a;i<(int)n;++i)
#define rep(...) SELECTER(__VA_ARGS__,rep2,rep1)(__VA_ARGS__)
#define RSELECTER(_1, _2, _3, RSELECT, ...) RSELECT
#define rrep1(i,n) for(int i=(int)n-1;i>=0;--i)
#define rrep2(i,a,n) for(int i=(int)n-1;i>=(int)a;--i)
#define rrep(...) RSELECTER(__VA_ARGS__, rrep2, rrep1)(__VA_ARGS__)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define fi first
#define se second
#define PrintR LogOutput
#ifdef _DEBUG
#define Log(...) LogOutput(__VA_ARGS__)
#else
#define Log(...)
#endif
using namespace std;
using ll=long long;
using pii=pair<int,int>;
using pll=pair<long long,long long>;
using pdd=pair<long double,long double>;
using veci=vector<int>;
using vecpii=vector<pair<int,int>>;
using vecll=vector<long long>;
using vecpll=vector<pair<long long,long long>>;
using vecpdd=vector<pair<long double,long double>>;
using vecs=vector<string>;
using vecb=vector<bool>;
using vecd=vector<long double>;
template<class T> inline bool chmax(T& a,T b){if(a<b) {a=b;return true;} return false;}
template<class T> inline bool chmin(T& a,T b){if(a>b) {a=b;return true;} return false;}

constexpr ll INF=numeric_limits<ll>::max() / 4;
constexpr ll MOD=998244353;
using tp=tuple<int,int,int>;
using tpll=tuple<ll,ll,ll>;

template<typename T>
T LogOutput(T a, bool b = true){
	if(b) cout << a << endl;
	return a;
}
template<typename... Args>
void LogOutput(Args&&... args){
	stringstream ss;
	((ss << LogOutput(args, false) << ' '), ...);
	cout << ss.str().substr(0, ss.str().length() - 1) << endl;
}
template<typename T>
void LogOutput(vector<T>& data){
	for(int i = 0 ; i < data.size() ; ++i){
		cout << LogOutput(data[i], false) << " \n"[i == data.size() - 1];
	}
}
template<typename T>
void LogOutput(vector<vector<T>>& data){
	for(auto d : data) LogOutput(d);
}

int main(){
	ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	int n;cin>>n;
	vecll x(n), y(n);
	rep(i, n) cin>>x[i]>>y[i];
	set<pll> st;
	int ans = 0;
	rep(i, n){
		rep(j, n){
			if(i == j) continue;
			ll a = x[i] - x[j], b = y[i] - y[j];
			ll g = gcd(a, b);
			a /= g; b /= g;
			if(st.count({a, b})){
				ans++;
				break;
			}else st.emplace(a, b);
		}
		set<pll> temp;
		swap(st, temp);
	}
	cout<<ans<<endl;
}