import os
import sys
from collections import *
from heapq import *
from math import gcd, floor, ceil, sqrt
from copy import deepcopy
from itertools import permutations, combinations, product
from bisect import bisect_left, bisect_right
from functools import lru_cache, reduce
import operator
from random import getrandbits
input = lambda: sys.stdin.readline().strip()
flush = lambda: sys.stdout.flush()
print = lambda *args, **kwargs: sys.stdout.write(' '.join(map(str, args)) + kwargs.get("end", "\n")) and flush()
sys.setrecursionlimit(100000)
MOD = 1000000007
MAX_NODES = 500010
def ints(): return map(int, input().split())
def strs(): return input().split()
def chars(): return list(input().strip())
def mat(n): return [list(ints()) for _ in range(n)]
AL = [[] for _ in range(MAX_NODES)]
visited = [0] * MAX_NODES
edge_visited = [0] * MAX_NODES
index_tracker = [0] * MAX_NODES
ans = [0] * MAX_NODES
def dfs(u, size):
visited[u] = 1
ans[size] = u
while index_tracker[u] < len(AL[u]):
v, edge_index = AL[u][index_tracker[u]]
index_tracker[u] += 1
if edge_visited[edge_index]:
continue
edge_visited[edge_index] = 1
if not visited[v]:
returned_node = dfs(v, size + 1)
if returned_node == u:
continue
else:
visited[u] = 0
return returned_node
else:
for j in range(size, -1, -1):
print(ans[j], end=" ")
if ans[j] == v:
break
print()
visited[u] = 0
return v
return 0
def solve():
n, m = ints()
for i in range(m):
u, v = ints()
AL[u].append((v, i))
AL[v].append((u, i))
for i in range(1, n + 1):
if not visited[i]:
dfs(i, 0)
def main():
solve()
if __name__ == "__main__":
main()
