import random

def generate_ring_preserving_network(T, test_cases):
    for t in range(T):
        C, L = test_cases[t]
        # Create a list of links from 1 to C
        links = [(i, (i + 1) % C + 1) for i in range(1, C+1)]
        # Shuffle the links
        random.shuffle(links)
        # Sort the links lexicographically
        links.sort()
        # Print the shuffled and sorted links
        for i in range(L):
            print(links[i][0], links[i][1])
        # Read the permuted design from the judge
        permuted_design = [tuple(map(int, input().split())) for _ in range(L)]
        # Find a ring in the permuted design
        ring = []
        current = permuted_design[0][0]
        for _ in range(C):
            ring.append(current)
            next_comp = -1
            for j in range(L):
                if permuted_design[j][0] == current:
                    next_comp = permuted_design[j][1]
                    permuted_design[j] = (-1, -1)
                    break
            current = next_comp
        # Print the ring
        print(*ring)