#include <bits/stdc++.h>
using namespace std;
#define EPS (1e-10)
#define REP (i,n) for (int i = 0; i<(n);i++)

typedef long double ld;
typedef long long ll;
typedef pair<int,int> ii;
typedef pair<double, double> dd;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<double> vd;

int main() {
    ios::sync_with_stdio(false);
    int N; cin >> N;
    vi x(N), y(N);
    set<pair<int, int>> s, sol;
    for(int i = 0; i < N; ++i){
        cin >> x[i] >> y[i];
        s.insert({x[i], y[i]});
    }
    ll res = 0;
    for(int i = 1; i < N; ++i) {
        int dx = x[i]-x[0], dy = y[i]-y[0];
        //cout << dx << " " << dy << endl;
        bool solv = true;
        for(int j = 0; j < N; ++j) {
            if (s.find({x[j]-dx, y[j]-dy}) == s.end() &&
                s.find({x[j]+dx, y[j]+dy}) == s.end()) {
                solv=false;break;
            }

        }
        if (solv) {
            sol.insert({dx, dy});
            sol.insert({-dx, -dy});
        }
    }
    cout << sol.size() << endl;
}