#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef long double ld;
typedef pair<ld, ld> point;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
 
const int N = (int)(20) + 7;
const int M = (int)(1e3) + 7;
const ll MOD = (ll)(998244353);
const ll INF = (ll)(1e10) + 7;
const ld eps = (ld)(1e-12);
 
#define pb push_back
#define mp make_pair
#define x first
#define y second

void precalc() {
}

void solve(int num_t) {
    int n;
    cin >> n;
    vector<pair<pii, int> > p(n);
    vector<int> mark(n);
    vector<pair<ll, pii> > d;
    for (int i = 0; i < n; ++i) {
        cin >> p[i].x.x >> p[i].x.y;
        p[i].y = i;
    }
    sort(p.begin(), p.end());
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < i; ++j) {
            d.pb(mp((ll)(p[i].x.x - p[j].x.x) * (ll)(p[i].x.x - p[j].x.x) + 
                (ll)(p[i].x.y - p[j].x.y) * (ll)(p[i].x.y - p[j].x.y), mp(i, j)));
        }
    }
    sort(d.begin(), d.end());
    vector<pii> ans;
    for (int i = 0; i < (int)(d.size()); ++i) {
        if (!mark[d[i].y.x] && !mark[d[i].y.y]) {
            ans.pb(d[i].y);
            mark[d[i].y.x] = 1;
            mark[d[i].y.y] = 1;
        }
    }
    cout << ans.size() << endl;
    for (int i = 0; i < (int)(ans.size()); ++i) {
        cout << ans[i].x + 1 << ' ' << ans[i].y + 1 << endl;
    }
}

int main() {
    precalc();
	/*int ttt;
	cin >> ttt;
	for (int i = 0; i < ttt; ++i) {
	    solve(i);
	}//*/solve(0);
	return 0;
}