import sys
input = lambda: sys.stdin.readline().rstrip()
# sys.setrecursionlimit(10**7)
# sys.set_int_max_str_digits(10**6)
# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')
def mp():return map(int,input().split())
def lmp():return list(map(int,input().split()))
def lm1(LIST): return list(map(lambda x:x-1, LIST))
def mps(A):return [tuple(map(int, input().split())) for _ in range(A)]
def stoi(LIST):return list(map(int,LIST))
def itos(LIST):return list(map(str,LIST))
def atoi(LIST): return [ord(i)-ord("a") for i in LIST]
def Atoi(LIST): return [ord(i)-ord("A") for i in LIST]
def LT(LIST,N): return LIST[bisect.bisect_left(LIST,N)-1]
def LE(LIST,N): return LIST[bisect.bisect_right(LIST,N)-1]
def GT(LIST,N): return LIST[bisect.bisect_right(LIST,N)]
def GE(LIST,N): return LIST[bisect.bisect_left(LIST,N)]
def bitA(X,A):return X & 1<<A == 1<<A
def gtoi(x,y,h,w):return x*w+y
import math
import bisect
import heapq
import time
import random as rd
import itertools
from copy import copy as cc
from copy import deepcopy as dc
from itertools import accumulate, product
from collections import Counter, defaultdict, deque
def ceil(U,V):return (U+V-1)//V
def modf1(N,MOD):return (N-1)%MOD+1
def printmat(list):
    for i in list:print(*i)
m4 = [[1,0],[0,1],[-1,0],[0,-1]]
m8 = [[-1,-1],[-1,0],[-1,1],[0,-1],[0,1],[1,-1],[1,0],[1,1]]
inf = (1<<63)-1
mod = 998244353

start_time = time.time()
n = int(input())
omote = []
ura = []
max_limit = 50
for i in range(n):
    a,b = mp()
    omote.append(a)
    ura.append(b)
width = 5
depth = 3

def output(sosa_arr):
    print(len(sosa_arr))
    for i,j in sosa_arr:print(i+1,j+1)

def calc_score(x,y):
    return max(abs(500000000000000000-x),abs(500000000000000000-y))

def calc_all_score(a,b,X):
    ErrorA = abs(500000000000000000 - a[0])
    ErrorB = abs(500000000000000000 - b[0])
    Score = (int)(2000000.0 - 100000.0 * math.log10(1.0 * max(ErrorA, ErrorB) + 1.0))
    if ErrorA == 0 and ErrorB == 0:
        Score = 2000050 - X
    return Score


def greedy(a,b):
    sosa = []
    for kaisu in range(max_limit):
        score = calc_score(a[0],b[0])
        choose_card = 0
        for i in range(1,n):
            na,nb = (a[0]+a[i])/2, (b[0]+b[i])/2
            now_score = calc_score(na,nb)
            if now_score < score:
                score = now_score
                choose_card = i
        a[0],b[0],a[choose_card],b[choose_card] = (a[0]+a[choose_card])/2, (b[0]+b[choose_card])/2,\
                                                  (a[0]+a[choose_card])/2, (b[0]+b[choose_card])/2
        if choose_card == 0:break
        sosa.append([0,choose_card])
    return a,b,sosa


def remove_huyou(A):
    while len(A) != 1:
        if A[-1] == A[-2]:A.pop()
        else:break
    return A


def hanei_0(Score,A,B,Sosa):
    choose_card = 0
    Score = calc_score(A[0],B[0])
    for i in range(1, n):
        na, nb = (A[0] + A[i]) / 2, (B[0] + B[i]) / 2
        now_score = calc_score(na, nb)
        if now_score < Score:
            Score = now_score
            choose_card = i
    A[0], B[0], A[choose_card], B[choose_card] = (A[0] + A[choose_card]) / 2, (B[0] + B[choose_card]) / 2, \
                                                 (A[0] + A[choose_card]) / 2, (B[0] + B[choose_card]) / 2
    if choose_card != 0:Sosa.append([0, choose_card])
    return [Score,A,B,Sosa]


def beam_search(a,b,sosa_Arr):
    koho = [[calc_score(a[0],b[0]), cc(a), cc(b), sosa_Arr]]  # 次stepで反映したときのscore,今のa,今のb,今の操作
    heapq.heapify(koho)
    best_score = calc_score(a[0],b[0])
    for dep in range(depth):
        now_koho = []
        while not (len(koho) == 0 or len(now_koho) == width):
            nxt = heapq.heappop(koho)
            if nxt[0] > best_score:break
            now_koho.append(nxt)
        koho.clear()
        #print("n",now_koho)
        best_score = now_koho[0][0]
        for Score,A,B,Sosa in now_koho:
            if len(Sosa) == max_limit:continue
            heapq.heappush(koho, dc([Score, A, B, Sosa]))
            for i in range(n):
                for j in range(i+1,n):
                    if Sosa and Sosa[-1] == [i,j]:continue
                    ac = cc(A)
                    bc = cc(B)
                    sosac = cc(Sosa)
                    na,nb = (a[i]+a[j])/2, (b[i]+b[j])/2
                    ac[i],ac[j],bc[i],bc[j] = na,na,nb,nb
                    hanei_a,hanei_b = (na+ac[0])/2, (nb+bc[0])/2
                    now_score = calc_score(hanei_a,hanei_b)
                    sosac.append([i,j])
                    heapq.heappush(koho,[now_score,ac,bc,sosac])
        #print(koho)
    best_koho = heapq.heappop(koho)
    best_koho[3] = remove_huyou(best_koho[3])
    best_koho = hanei_0(*best_koho)
    return best_koho


def main():
    sosa_arr = []
    global omote
    global ura
    while time.time()-start_time <= 0.8:
        pred_score,na,nb,sosa_arr = beam_search(omote,ura,sosa_arr)
        omote = na
        ura = nb
        #print(pred_score,omote,ura,sosa_arr)
    output(sosa_arr)
    #print(calc_all_score(omote,ura,len(sosa_arr)))
    #na,nb,sosa_arr = greedy(omote,ura)

main()