#include <iostream>
#include <array>
#include <algorithm>
#include <vector>
#include <bitset>
#include <set>
#include <unordered_set>
#include <cmath>
#include <complex>
#include <deque>
#include <iterator>
#include <numeric>
#include <map>
#include <unordered_map>
#include <queue>
#include <stack>
#include <string>
#include <tuple>
#include <utility>
#include <limits>
#include <iomanip>
#include <functional>
#include <cassert>
using namespace std;

using ll=long long;
template<class T> using V = vector<T>;
template<class T, class U> using P = pair<T, U>;
using vll = V<ll>;
using vvll = V<vll>;
#define ALL(v) v.begin(),v.end()
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; }
#define DEBUG_VLL(vec) REP(sz, vec.size()) std::cerr<<vec[sz]<<(sz==vec.size()-1?'\n':' ');

const long long MOD = 1000000007;
const long long HIGHINF = (long long)1e18;
const int INF = (int)1e9;

using PI = P<ll, ll>;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n; cin >> n;
    V<PI> xy(n);
    for (int i = 0; i < n; i++) cin >> xy[i].first >> xy[i].second;
    V< P<ll, PI> > time;
    for (int i = 0; i < n; i++) {
        for (int j = i + 1; j < n; j++) {
            double t = (xy[i].first - xy[j].first) * (xy[i].first - xy[j].first) + (xy[i].second - xy[j].second) * (xy[i].second - xy[j].second);
            time.emplace_back(t, PI(i, j));
        }
    }
    sort(ALL(time));

    V<bool> broken(n, false);
    int ans = 0;
    ll tmp = 0, se0 = 0;
    set<int> bl;
    for (P<ll, PI> ttt: time) {
        if (ttt.first != tmp) {
            ans += se0;
            se0 = 0;
            for (int b: bl) broken[b] = true;
            bl.clear();
        }

        if (ttt.second.first == 0) {
            if (broken[ttt.second.second]) continue;
            else se0++, broken[ttt.second.second] = true;
        } else if (ttt.second.second == 0) {
            if (broken[ttt.second.first]) continue;
            else se0++, broken[ttt.second.second] = true;
        } else {
            if (!broken[ttt.second.first] and !broken[ttt.second.second]) {
                bl.insert(ttt.second.first), bl.insert(ttt.second.second);
            }
        }
        tmp = ttt.first;
    }
    ans += se0;
    cout << ans << '\n';
    return 0;
}