from time import time
start = time()
import sys,math
from random import randint,randrange,sample,shuffle,choice
def input(): return sys.stdin.readline().rstrip()
def ii(): return int(input())
def ms(): return map(int, input().split())
def li(): return list(map(int,input().split()))
# ////////////////////////////////
N = ii()
A = list()
B = list()
for i in range(N):
  a,b = ms()
  A.append([a,i])
  B.append([b,i])
NUM = [i for i in range(N)]
STAND = 5*pow(10,17)
TURN = 0
V1,V2 = abs(A[0][0]-STAND),abs(B[0][0]-STAND)
ANS = list()
while TURN<50:
  if time()-start>0.85: break
  v = choice(NUM)
  na,nb = (A[0][0]+A[v][0])//2,(B[0][0]+B[v][0])//2
  n1,n2 = abs(na-STAND),abs(nb-STAND)
  if max(n1,n2)>=max(V1,V2): continue
  ANS.append((1,v))
  V1,V2 = n1,n2
  A[0][0],A[v][0],B[0][0],B[v][0] = na,na,nb,nb
  TURN += 1
  
print(len(ANS))
for u,v in ANS: print(u,v)