import sys
import math
import bisect
from heapq import heapify, heappop, heappush
from collections import deque, defaultdict, Counter
from functools import lru_cache
from itertools import accumulate, combinations, permutations, product

sys.setrecursionlimit(1000000)
MOD = 10 ** 9 + 7
MOD99 = 998244353

input = lambda: sys.stdin.readline().strip()
NI = lambda: int(input())
NMI = lambda: map(int, input().split())
NLI = lambda: list(NMI())
SI = lambda: input()
SMI = lambda: input().split()
SLI = lambda: list(SMI())
EI = lambda m: [NLI() for _ in range(m)]


def score(a, b, x):
    v1 = abs(5 * 10**17 - a)
    v2 = abs(5 * 10**17 - b)
    if max(v1, v2) > 0:
        return int(2000000 - 100000 * math.log10(max(v1, v2)+1))
    else:
        return 2000050 - x


def answer(ans):
    print(len(ans))
    for i, j in ans:
        print(i+1, j+1)


def greedy():
    N = NI()
    AB = EI(N)

    ans = []
    # 0と何かだけで貪欲
    for qi in range(50):
        a0, b0 = AB[0]
        s = score(a0, b0, qi)
        best_s = s
        best_v = 1
        for v in range(1, N):
            av, bv = AB[v]
            na, nb = (a0+av) // 2, (b0+bv) // 2
            ns = score(na, nb, qi+1)

            if ns > best_s:
                best_s = ns
                best_v = v

        if best_s > s:
            av, bv = AB[best_v]
            na, nb = (a0 + av) // 2, (b0 + bv) // 2
            AB[0] = [na, nb]
            AB[best_v] = [na, nb]
            ans.append([0, best_v])
        else:
            break

    answer(ans)


def means(AB, i, j):
    ai, bi = AB[i]
    aj, bj = AB[j]
    na, nb = (ai + aj) // 2, (bi + bj) // 2
    return na, nb


def query(AB, i, j):
    na, nb = means(AB, i, j)
    AB[i] = [na, nb]
    AB[j] = [na, nb]


def total_score(AB):
    res = 0
    for a, b in AB:
        res += score(a, b, 0)
    return res


def calc_gap(AB, i, j):
    # ABについてi, jを操作したときのスコアの差分
    na, nb = means(AB, i, j)
    after = score(na, nb, 0) * 2
    before = score(AB[i][0], AB[i][1], 0) + score(AB[j][0], AB[j][1], 0)
    return after - before


def main():
    N = NI()
    AB = EI(N)

    total = total_score(AB)
    ans = []

    # totalが改善するように山登り
    for qi in range(50):

        max_gap = 0
        best_ij = [0, 1]
        for i in range(N):
            for j in range(i+1, N):
                gap = calc_gap(AB, i, j)
                if gap > max_gap:
                    max_gap = gap
                    best_ij = [i, j]
        if max_gap > 0:
            query(AB, *best_ij)
            ans.append(best_ij)
        else:
            break

    answer(ans)


if __name__ == "__main__":
    main()