#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using ld=double;
#define FOR(i,a,b) for(ll i=a;i<(ll)b;++i)
#define F(n) FOR(i,0,n)
#define FF(n) FOR(j,0,n)
#define aa first
#define bb second
#define PB push_back
#define EQ(a,b) (fabs(a-b)<=(fabs(a+b)*EPS))

int main(){
	ios::sync_with_stdio(0);cout.tie(0);cin.tie(0);
  ll n;
  cin >> n;
  set<pair<int,int>> a;
  F(n) {
    ll x, y;
    cin >> x >> y;
    a.insert({x,y});
  }
  ll res = 0;
 
  pair<int,int> c = *a.begin();
  for (auto i: a) {
    pair<int,int> v = {c.aa - i.aa, c.bb - i.bb};
    if (v.aa == 0 && v.bb == 0) continue;
    // test if correct
    bool ok = true;
    for (auto j: a) {
      if (!a.count({j.aa + v.aa, j.bb + v.bb}) &&
        !a.count({j.aa - v.aa, j.bb - v.bb})) {
        ok = false;
        break;
      }
    }
    res += ok*2;
  }
  cout << res << endl;

	return 0;
}