#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define REPR(i, n) for (int i = n - 1; i >= 0; --i)
#define FOR(i, m, n) for (int i = m; i < n; ++i)
#define FORR(i, m, n) for (int i = m; i >= n; --i)
#define ALL(v) (v).begin(),(v).end()
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
const ll INF=1LL<<60;
const int inf=(1<<30)-1;
const int mod=1e9+7;
int dx[8]={1,0,-1,0,-1,-1,1,1};
int dy[8]={0,1,0,-1,-1,1,-1,1};
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;cin >> n;
    vector<ll> x(n),y(n);
    REP(i,n){
        cin >> x[i] >> y[i];
    }
    vector<vector<ll>> d(n,vector<ll>(n,INF));
    vector<pair<ll,pair<int,int>>> p;
    REP(i,n){
        FOR(j,i+1,n){
            d[i][j]=d[j][i]=(x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]);
            p.push_back({d[i][j],{i,j}});
        }
    }
    sort(ALL(p));
    vector<bool> b(n);
    int ans=0;
    for(auto x:p){
        ll u=x.first,v=x.second.first,w=x.second.second;
        if(!b[v]&&!b[w]){
            if(v==0){
                b[w]=true;
                ans++;
            }
            else{
                b[v]=b[w]=true;
            }
        }
    }
    if((n-ans)%2==0){
        ans++;
    }
    cout << ans << endl;
}