#pragma GCC optimize("O3")
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <cfloat>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <fstream>
#include <functional>
#include <bitset>
using namespace std;

using ll = long long;
using P = pair<int, int>;
using T = tuple<int, int, int>;

template <class T> inline T chmax(T &a, const T b) {return a = (a < b) ? b : a;}
template <class T> inline T chmin(T &a, const T b) {return a = (a > b) ? b : a;}

constexpr int MOD = 1e9 + 7;
constexpr int inf = 1e9;
constexpr long long INF = 1e18;

#define all(a) (a).begin(), (a).end()

int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};

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

    int n; cin>>n;
    vector<ll> x(n), y(n);
    for(int i=0; i<n; i++) cin>>x[i]>>y[i];

    set<tuple<ll, ll, ll>> po;
    for(int i=1; i<n; i++){
        ll dist = abs(x[0] - x[i]) * abs(x[0] - x[i]) + abs(y[0] - y[i]) * abs(y[0] - y[i]);
        po.emplace(dist, x[i], y[i]);
    }

    auto bpo = po;

    for(auto i:bpo){
        ll cdist, cx, cy;
        tie(cdist, cx, cy) = i;
        
        bool reach = true;
        for(auto j:po){
            ll ndist, nx, ny;
            tie(ndist, nx, ny) = j;

            if(cdist == ndist && cx == nx && cy == ny) continue;
            
            ll dist = abs(cx - nx) * abs(cx - nx) + abs(cy - ny) * abs(cy - ny);
            if(dist < cdist) reach = false;
        }

        if(reach){
            po.erase(make_tuple(cdist, cx, cy));
        }
    }

    cout << (n - 1) - po.size() << endl;

    return 0;
}