from queue import Queue

n = int(input())

tree = {i: [] for i in range(1, n + 1)}

for i in range(n - 1):
    a, b, c = map(int, input().strip().split())

    tree[a].append((b, c))
    tree[b].append((a, c))

keys = list(tree)

bad_paths = {}


def recdel(n, root):
    global bad_paths

    if bad_paths == 'ALL':
        return

    q = Queue()
    q.put((n, root))

    while not q.empty():
        n, root = q.get()

        if n not in tree:
            continue

        if n in bad_paths and bad_paths[n] == root:
            continue

        if root in bad_paths and bad_paths[root] == n:
            bad_paths = 'ALL'  # needs global
            return

        bad_paths[n] = root

        neighbors = tree[n]

        for e, _ in neighbors:
            if e == root:
                continue
            q.put((e, n))


for f in keys:
    if f not in tree:
        continue

    edges = tree[f]
    all_colors = set()
    bad_colors = set()

    for t, c in edges:
        if c in all_colors:
            bad_colors.add(c)
        else:
            all_colors.add(c)

    for t, c in edges:
        if c in bad_colors:
            recdel(t, f)

all_good = set()
if bad_paths != 'ALL':
    all_good = set(tree) - set(bad_paths)

print(len(all_good))
for i in sorted(all_good):
    print(i)