from igraph import *
from union_find import UnionFind
# Union find from git@github.com:deehzee/unionfind.git

def mst_kruskal(G):
    c = G.get_edgelist()
    w = [G[i] for i in c]

    c = [x for _,x in sorted(zip(w,c))]

    uf = UnionFind(G.vs.indices)
    T = Graph(len(G.vs.indices))

    for e in c:
        if not uf.connected(e[0], e[1]):
            T.add_edge(e[0], e[1])
            uf.union(e[0], e[1])
    return T

if __name__ == '__main__':
    n, m = [int(i) for i in input().split(' ')]
    g = Graph(n)
    g.es["weight"] = 1.0

    for i in range(m):
        a, b, w = [int(i) for i in input().split(' ')]
        print(a, b)
        g.add_edge(a, b)
        g[a, b] = w

    mst = mst_kruskal(g)
    plot(mst)