1583B - Omkar and Heavenly Tree - CodeForces Solution

def main():
    
    t = int(input())
    allans = []
    for _ in range(t):
        n, m = readIntArr()
        inmiddle = [0] * (n + 1)
        for __ in range(m):
            a, b, c = readIntArr()
            inmiddle[b] = 1
                central = -1
        for u in range(1, n + 1):
            if inmiddle[u] == 0:
                central = u
                break
        assert central != -1
        for v in range(1, n + 1):
            if u == v:
                continue
            allans.append((u, v))
    multiLineArrayOfArraysPrint(allans)
    
    return

import sys
input=sys.stdin.buffer.readline  
def oneLineArrayPrint(arr):
    print(' '.join([str(x) for x in arr]))
def multiLineArrayPrint(arr):
    print('\n'.join([str(x) for x in arr]))
def multiLineArrayOfArraysPrint(arr):
    print('\n'.join([' '.join([str(x) for x in y]) for y in arr]))
 
def readIntArr():
    return [int(x) for x in input().split()]
 
def makeArr(defaultValFactory,dimensionArr):     dv=defaultValFactory;da=dimensionArr
    if len(da)==1:return [dv() for _ in range(da[0])]
    else:return [makeArr(dv,da[1:]) for _ in range(da[0])]
 
def queryInteractive(a, b, c):
    print('? {} {} {}'.format(a, b, c))
    sys.stdout.flush()
    return int(input())
 
def answerInteractive(x1, x2):
    print('! {} {}'.format(x1, x2))
    sys.stdout.flush()
 
inf=float('inf')
 
from math import gcd,floor,ceil
import math
 
for _abc in range(1):
    main()