use std::cmp::{max, min};
use std::io;
use std::collections::BinaryHeap;
use std::time::Instant;


#[derive(Debug, Clone)]
struct Node {
    cards: Vec<(i64, i64)>,
    score: i64,
    score2: i64,
    history: Vec<(usize, usize)>,
}
impl Eq for Node {}
impl PartialEq for Node {
    fn eq(&self, other: &Self) -> bool {
        self.score == other.score
    }
}
impl Ord for Node {
    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
        self.score.cmp(&other.score)
    }
}
impl PartialOrd for Node {
    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
        Some(self.cmp(other))
    }
}

impl Node {
    fn new(cards: Vec<(i64, i64)>, history: Vec<(usize, usize)>, calced_score: i64) -> Self {
        let mut score = calced_score;
        if score <= -1 {
            score = Self::calc_score(&cards);
        }
        let score2 = Self::calc_score_2(&cards);
        Self {
            cards,
            score,
            score2,
            history,
        }
    }

    fn calc_score(cards: &Vec<(i64, i64)>) -> i64 {
        let mut max_score = 2000000;
        let target = 10_i64.pow(17) * 5;
        let mut result_score = 0;
        for i in 1..cards.len() {
            let new_card = ((cards[i].0 + cards[0].0) / 2, (cards[i].1 + cards[0].1) / 2);
            result_score = max(result_score, max_score - (100000.0 * (max((new_card.0 - target).abs(), (new_card.1 - target).abs()) as f64 + 1.0).log10()) as i64);
        }
        result_score
    }

    fn calc_score_2(cards: &Vec<(i64, i64)>) -> i64 {
        let mut max_score = 2000000;
        let target = 10_i64.pow(17) * 5;
        max_score - (100000.0 * (max((cards[0].0 - target).abs(), (cards[0].1 - target).abs()) as f64 + 1.0).log10()) as i64
    }

    fn build_next(&self, turn: (usize, usize)) -> Self {
        let mut cards = self.cards.clone();
        let new_card = ((cards[turn.0].0 + cards[turn.1].0) / 2, (cards[turn.0].1 + cards[turn.1].1) / 2);
        cards[turn.0] = new_card;
        cards[turn.1] = new_card;
        let mut history = self.history.clone();
        history.push(turn);
        if turn.0 == 0 {
            Self::new(cards, history, -1)
        } else {
            let new_card_0 = ((cards[0].0 + new_card.0) / 2, (cards[0].1 + new_card.1) / 2);
            let mut score = self.score;
            let target = 10_i64.pow(17) * 5;
            score = max(score, 2000000 - (100000.0 * (max((new_card_0.0 - target).abs(), (new_card_0.1 - target).abs()) as f64 + 1.0).log10()) as i64);

            Self::new(cards, history, score)
        }
    }
}

struct Solver {
    n: usize,
    states: Vec<BinaryHeap<Node>>,
    searched_states: Vec<BinaryHeap<Node>>,
    time: Instant,
}

impl Solver {
    fn new(n: usize, cards: Vec<(i64, i64)>) -> Self {
        let mut states = vec![BinaryHeap::new(); 51];
        let node = Node::new(cards, vec![], -1);
        states[0].push(node);
        let mut searched_states = vec![BinaryHeap::new(); 51];
        let time = Instant::now();
        Self { n, states, searched_states, time }
    }

    fn solve(&mut self) {
        let n = self.n;
        let target = 10_i64.pow(17) * 5;
        let time = Instant::now();
        let mut itr = 0;
        while self.time.elapsed().as_millis() < 900 {
            itr += 1;
            for i in 0..50 {
                if self.time.elapsed().as_millis() >= 900 {
                    return;
                }
                let state = &self.states[i].pop();
                if state.is_none() {
                    continue;
                }
                let state = state.as_ref().unwrap();
                let cards = &state.cards;
                // eprintln!("{}: {}", itr, i + 1);
                // let mut best_score = BinaryHeap::new();
                let mut new_states = BinaryHeap::new();
                for p in 0..n {
                    for q in p + 1..n {
                        let next_state = state.build_next((p, q));
                        new_states.push(next_state);
                        
                        if self.time.elapsed().as_millis() >= 900 {
                            return;
                        }
                    }
                }
                for _ in 0..min(100, new_states.len()) {
                    let state = new_states.pop().unwrap();
                    self.states[i + 1].push(state.clone());
                        
                    if self.time.elapsed().as_millis() >= 900 {
                        return;
                    }
                }
                self.searched_states[i].push(state.clone());
            }
        }
    }

    fn print(&self) {
        let mut ans_state = None;
        for i in 0..51 {
            if !self.states[i].is_empty() {
                if ans_state.is_none() {
                    ans_state = Some(self.states[i].peek().unwrap().clone());
                }
                if self.states[i].peek().unwrap().score2 > ans_state.as_ref().unwrap().score2 {
                    ans_state = Some(self.states[i].peek().unwrap().clone());
                }
            }
            if !self.searched_states[i].is_empty() {
                if ans_state.is_none() {
                    ans_state = Some(self.searched_states[i].peek().unwrap().clone());
                }
                if self.searched_states[i].peek().unwrap().score2 > ans_state.as_ref().unwrap().score2 {
                    ans_state = Some(self.searched_states[i].peek().unwrap().clone());
                }
            }
            // eprintln!("{}: {}", i + 1, self.states[i].len() + self.searched_states[i].len());
        }
        let ans_state = ans_state.unwrap();
        let ans = &ans_state.history;
        println!("{}", ans.len());
        for a in ans {
            println!("{} {}", a.0 + 1, a.1 + 1);
        }
        /*
        for i in 0..self.n {
            eprintln!("{}: {:?}", i + 1, ans_state.cards[i]);
        }
        */
    }
}

fn main() {
    let mut buffer = String::new();
    io::stdin().read_line(&mut buffer).unwrap();
    let n: usize = buffer.trim().parse().unwrap();
    let mut cards = vec![];
    for _ in 0..n {
        let mut buffer = String::new();
        io::stdin().read_line(&mut buffer).unwrap();
        let mut iter = buffer.trim().split_whitespace();
        let x: i64 = iter.next().unwrap().parse().unwrap();
        let y: i64 = iter.next().unwrap().parse().unwrap();
        cards.push((x, y));
    }
    let mut solver = Solver::new(n, cards);
    solver.solve();
    solver.print();
}