import copy
import random
from time import perf_counter
import argparse
import sys
import math

class TimeKeeper:
    def __init__(self):
        self.start_time = perf_counter()
    def is_time_over(self, LIMIT):
        return (perf_counter() - self.start_time) >= LIMIT
    def time_now(self):
        return (perf_counter() - self.start_time)

def calscore(ans, C0):
    C = C0[:]
    X = len(ans)
    sc = 0
    for i in range(X):
        u, v = ans[i]
        a0, b0 = C[u]
        a1, b1 = C[v]
        C[u] = (a0 + a1)//2, (b0 + b1)//2
        C[v] = (a0 + a1)//2, (b0 + b1)//2
    V1 = abs(C[0][0] - 5*10**17)
    V2 = abs(C[0][1] - 5*10**17)
    sc = int(2*10**6 - 10**5 * math.log10(max(V1, V2) + 1))
    return sc


###########################################
def main(DEBUG):
    tk = TimeKeeper()
    if DEBUG == True:
        LIMIT = 0.85
    else:
        LIMIT = 0.85

    def output(ans):
        print(len(ans))
        for i in range(len(ans)):
            u, v = ans[i]
            u += 1
            v += 1
            print(u, v)
        return

    def solve1(LIMIT):
        C = C0[:]
        ans = []
        a0 = C[0][0]
        b0 = C[0][1]
        V1 = abs(a0 - 5*10**17)
        V2 = abs(b0 - 5*10**17)
        nowV = max(V1, V2)
        while len(ans) < 50:
            if tk.is_time_over(LIMIT):
                break
            for i in range(1, N):
                ai, bi = C[i][0], C[i][1]
                nxV1 = abs((a0 + ai) // 2 - 5*10**17)
                nxV2 = abs((b0 + bi) // 2 - 5*10**17)
                nxtV = max(nxV1, nxV2)
                if nxtV < nowV:
                    nowV = nxtV
                    a0 = (a0 + ai) // 2
                    b0 = (b0 + bi) // 2
                    C[i] = (a0, b0)
                    ans.append((0, i))
                    sc = int(2*10**6 - 10**5 * math.log10(nowV + 1))
                    print(sc, nowV, a0, b0, file=sys.stderr)
        return ans

    def solve2(LIMIT):
        C = C0[:]
        ans = []
        a0 = C[0][0]
        b0 = C[0][1]
        V1 = abs(a0 - 5*10**17)
        V2 = abs(b0 - 5*10**17)
        nowV = max(V1, V2)
        finish = False
        while len(ans) < 50 and finish == False:
            finish = True
            for i in range(1, N):
                ai, bi = C[i][0], C[i][1]
                nxV1 = abs((a0 + ai) // 2 - 5*10**17)
                nxV2 = abs((b0 + bi) // 2 - 5*10**17)
                nxtV = max(nxV1, nxV2)
                if nxtV < nowV:
                    nowV = nxtV
                    a0 = (a0 + ai) // 2
                    b0 = (b0 + bi) // 2
                    C[i] = (a0, b0)
                    ans.append((0, i))
                    sc = int(2*10**6 - 10**5 * math.log10(nowV + 1))
                    print(sc, nowV, a0, b0, file=sys.stderr)
                    finish = False

        ###
        while True:
            if tk.is_time_over(LIMIT):
                print("timeover", file=sys.stderr)
                break
            inow = random.randint(1, N-1)
            a0 = C[inow][0]
            b0 = C[inow][1]
            V1 = abs(a0 - 5*10**17)
            V2 = abs(b0 - 5*10**17)
            nowV = max(V1, V2)
            finish = False
            while len(ans) < 50 and finish == False:
                finish = True
                for i in range(1, N):
                    if i == inow:
                        continue
                    ai, bi = C[i][0], C[i][1]
                    nxV1 = abs((a0 + ai) // 2 - 5*10**17)
                    nxV2 = abs((b0 + bi) // 2 - 5*10**17)
                    nxtV = max(nxV1, nxV2)
                    if nxtV < nowV:
                        nowV = nxtV
                        a0 = (a0 + ai) // 2
                        b0 = (b0 + bi) // 2
                        C[i] = (a0, b0)
                        ans.append((inow, i))
                        # sc = int(2*10**6 - 10**5 * math.log10(nowV + 1))
                        # print(sc, nowV, a0, b0, file=sys.stderr)
                        finish = False

            a0 = C[0][0]
            b0 = C[0][1]
            V1 = abs(a0 - 5*10**17)
            V2 = abs(b0 - 5*10**17)
            nowV = max(V1, V2)
            finish = False
            while len(ans) < 50 and finish == False:
                finish = True
                for i in range(1, N):
                    ai, bi = C[i][0], C[i][1]
                    nxV1 = abs((a0 + ai) // 2 - 5*10**17)
                    nxV2 = abs((b0 + bi) // 2 - 5*10**17)
                    nxtV = max(nxV1, nxV2)
                    if nxtV < nowV:
                        nowV = nxtV
                        a0 = (a0 + ai) // 2
                        b0 = (b0 + bi) // 2
                        C[i] = (a0, b0)
                        ans.append((0, i))
                        sc = int(2*10**6 - 10**5 * math.log10(nowV + 1))
                        print(sc, nowV, a0, b0, file=sys.stderr)
                        finish = False
        return ans

    def solve3(LIMIT):
        C = C0[:]
        ans = []

    N = int(input())
    C0 = []
    for i in range(N):
        a, b = map(int, input().split())
        C0.append((a, b))

    ans = solve2(LIMIT)
    sc = calscore(ans[:50], C0)

    print("SC", sc, file=sys.stderr)    
    output(ans[:50])
    return
    

if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Debug mode')
    parser.add_argument('--debug', action='store_true', help='Enable debug mode')
    args = parser.parse_args()
    main(args.debug)