def allPathsSourceTarget(graph,n):
    ans = list()
    stk = list()

    def dfs(x: int):
        if x == n:
            ans.append(stk[:])
            return
        
        for y in graph[x]:
            stk.append(y)
            dfs(y)
            stk.pop()
    
    stk.append(1)
    dfs(1)
    return ans  if len(ans) !=0 else -1


n,m = list(map(int,input().split()))
import collections
graph = collections.defaultdict(list)
for i in range(m):
    path = list(map(int,input().split()))
    graph[path[0]].append(path[1])

paths = allPathsSourceTarget(graph,n)
if paths == -1:
    print(-1)
else:
    for path in paths:
        print(' '.join(map(str, path)))