import sys
sys.setrecursionlimit(10000000)
N,M,K = map(int, raw_input().split())

graph = [[] for i in range(N)]
ans = set()
visit = [[-1 for i in range(K)] for j in range(N)]

def dfs(pos, path):
    if (path == K):
        return True
    global visit
    global d
    
    if (visit[pos][path] != -1):
        return visit[pos][path]
    ok = False
    for next in graph[pos]:
        if (d[path] != next[1]):
            continue
        ok |= dfs(next[0], path + 1)
    visit[pos][path] = ok
    return ok

for i in range(M):
    a,b,c = map(int, raw_input().split())
    a -= 1;b -= 1
    graph[a].append((b, c))
    graph[b].append((a, c))
d = map(int, raw_input().split())
d.reverse()
for i in range(N):
    if (dfs(i, 0)):
        ans.add(i)

ans = list(ans)
ans.sort()
ans = map(lambda x : x + 1, ans)
print len(ans)
if (len(ans) == 1):
    print ans[0]
else:
    print " ".join(map(str, ans))