There is a programing contest named SnakeUp, 2*n* people want to compete for it. In order to attend this contest, people need to form teams of exactly two people. You are given the strength of each possible combination of two people. All the values of the strengths are distinct.

Every contestant hopes that he can find a teammate so that their team’s strength is as high as possible. That is, a contestant will form a team with highest strength possible by choosing a teammate from ones who are willing to be a teammate with him/her. More formally, two people *A* and *B* may form a team if each of them is the best possible teammate (among the contestants that remain unpaired) for the other one. 

Can you determine who will be each person’s teammate?
There are 2*n* lines in the input. 

The first line contains an integer *n* (1 ≤ *n* ≤ 400) — the number of teams to be formed.

The *i*-th line (*i* &gt; 1) contains *i* - 1 numbers *a*<sub class="lower-index">*i*1</sub>, *a*<sub class="lower-index">*i*2</sub>, ... , *a*<sub class="lower-index">*i*(*i* - 1)</sub>. Here *a*<sub class="lower-index">*ij*</sub> (1 ≤ *a*<sub class="lower-index">*ij*</sub> ≤ 10<sup class="upper-index">6</sup>, all *a*<sub class="lower-index">*ij*</sub> are distinct) denotes the strength of a team consisting of person *i* and person *j* (people are numbered starting from 1.)
'''
###### * User Profile : Keval_78
LinkedIn: https://www.linkedin.com/in/kevalpadsala78/
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Leetcode: https://leetcode.com/Keval_78/
'''

import sys
from os import path
from math import log2, floor, ceil, sqrt, pow, gcd
# from random import random, randint, shuffle, choice
from collections import Counter, defaultdict, deque
# from itertools import permutations, combinations
# from functools import reduce
# from heapq import heapify, heappop, heappush, heapreplace
from bisect import bisect_left, bisect_right


def si(): return sys.stdin.readline().strip()
def ii(): return int(si())
def mi(ss=" "): return map(int, si().split(ss))
def msi(ss=" "): return map(str, si().split(ss))
def li(ss=" "): return list(mi(ss))


sys.setrecursionlimit(10 ** 5)
MOD, MOD2, INF = 10 ** 9 + 7, 998244353, float('inf')
MAX = 10**5+1

n = ii()
teams = [0 for i in range(2*n)]
arr = []
for i in range(2*n-1):
    temp = li()
    for i in range(len(temp)):
        temp[i] = [temp[i], i+1]
    arr.append(sorted(temp, reverse=True))

# for a in arr:
#     print(a)

for i in range(n):
    curr_max, candidate1, candidate2 = 0, 0, 0
    for i in range(2*n-1):
        if teams[i+1] != 0: continue
        max_ind = -1
        for ind, val in enumerate(arr[i]):
            if teams[val[1]-1] == 0:
                max_ind = ind
                break
        if max_ind != -1 and curr_max < arr[i][max_ind][0]:
            curr_max, candidate1, candidate2 = arr[i][max_ind][0], i+2, arr[i][max_ind][1]
    #print(curr_max, candidate1, candidate2)
    teams[candidate1-1], teams[candidate2-1] = candidate2, candidate1
print(*teams)
    
