#pragma GCC optimize("O3")
#pragma GCC optimize(2)
#pragma GCC optimize(3)
#pragma GCC optimize("Ofast")
#pragma GCC optimize("inline")
#pragma GCC optimize("-fgcse")
#pragma GCC optimize("-fgcse-lm")
#pragma GCC optimize("-fipa-sra")
#pragma GCC optimize("-ftree-pre")
#pragma GCC optimize("-ftree-vrp")
#pragma GCC optimize("-fpeephole2")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-fsched-spec")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("-falign-jumps")
#pragma GCC optimize("-falign-loops")	
#pragma GCC optimize("-falign-labels")
#pragma GCC optimize("-fdevirtualize")
#pragma GCC optimize("-fcaller-saves")
#pragma GCC optimize("-fcrossjumping") 
#pragma GCC optimize("-fthread-jumps")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("-freorder-blocks")
#pragma GCC optimize("-fschedule-insns")
#pragma GCC optimize("inline-functions")
#pragma GCC optimize("-ftree-tail-merge")
#pragma GCC optimize("-fschedule-insns2")
#pragma GCC optimize("-fstrict-aliasing")
#pragma GCC optimize("-falign-functions")
#pragma GCC optimize("-fcse-follow-jumps")
#pragma GCC optimize("-fsched-interblock")
#pragma GCC optimize("-fpartial-inlining")
#pragma GCC optimize("no-stack-protector")
#pragma GCC optimize("-freorder-functions")
#pragma GCC optimize("-findirect-inlining")
#pragma GCC optimize("-fhoist-adjacent-loads")
#pragma GCC optimize("-frerun-cse-after-loop")
#pragma GCC optimize("inline-small-functions")
#pragma GCC optimize("-finline-small-functions")
#pragma GCC optimize("-ftree-switch-conversion")
#pragma GCC optimize("-foptimize-sibling-calls")
#pragma GCC optimize("-fexpensive-optimizations")
#pragma GCC optimize("inline-functions-called-once")
#pragma GCC optimize("-fdelete-null-pointer-checks")
#pragma GCC optimize("Ofast")
//#pragma GCC target("avx,avx2,fma") 
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native") 
//#pragma GCC optimization ("unroll-loops")

#include <bits/stdc++.h>

using namespace std;

// 가장 가까이 있는 거 고르면 될 듯.

vector <int> adj[8000];
bool visited[8000];
int n,m,t,A[8000],B[8000];

bool dfs(int a)
{
    visited[a] = true;
    for(auto b : adj[a])
    {
        if(B[b]==-1 || !visited[B[b]] && dfs(B[b]))
        {
            A[a] = b;
            B[b] = a;
            return true;
        }
    }

    return false;
}

int gcd(int x,int y)
{
    if(y==0) return x;
    return gcd(y,x%y);
}

bool cmp(pair<pair<int,int>,int> a,pair<pair<int,int>,int> b)
{
    int A = a.first.first*a.first.first + a.first.second*a.first.second;
    int B = b.first.first*b.first.first + b.first.second*b.first.second;
    if(A==B)
    {
        return a.first.first < b.first.first;
    }
    return A < B;
}
int main(void) 
{
	cin.tie(0);
	ios::sync_with_stdio(false);

    int n,x,y;
    vector <pair<pair<int,int>,int>> v;

    cin >> n;

    for(int i=0;i<n;i++)
    {
        cin >> x >> y;
        v.push_back(make_pair(make_pair(x,y),i));
    }

    sort(v.begin(),v.end());

    
    set <int> S;
    vector <pair<int,int>> res;
    for(int i=0;i<n;i++)
    {
        if(S.find(v[i].second)!=S.end()) continue;
        vector <pair<pair<int,int>,int>> vec;
        for(int j=i+1;j<n;j++)
        {
            if(i==j) continue;
            int dx = v[i].first.first - v[j].first.first;
            int dy = v[i].first.second - v[j].first.second;
            vec.push_back(make_pair(make_pair(dx,dy),v[j].second));
        }
        sort(vec.begin(),vec.end(),cmp);

        for(int j=0;j<vec.size();j++)
        {
            int dx = vec[j].first.first;
            int dy = vec[j].first.second;
            if(S.find(vec[j].second)!=S.end()) continue;
            S.insert(v[i].second);
            S.insert(vec[j].second);
            res.push_back(make_pair(v[i].second+1,vec[j].second+1));
            break;
        }
    }

    cout << res.size() << '\n';

    for(auto it : res)
    {
        cout << it.first << ' ' << it.second << '\n';
    }


	return 0;
}