import itertools

H, W, K, P = map(int, input().split())

coordinates = dict()
name = [''] * K
for i in range(K):
    x, y, n = input().split()
    coordinates[(int(y), int(x))] = i
    name[i] = n

ans = 0
indices = ()
for t in itertools.combinations(range(K), P):
    table = [[0] * (H + 2) for _ in range(W + 2)]
    table[1][1] = 1
    it = itertools.product(range(W + 1), range(H + 1))
    next(it)
    for w, h in it:
        if (w, h) not in coordinates or coordinates[(w, h)] in t:
            table[w + 1][h + 1] = table[w][h + 1] + table[w + 1][h]
    if ans < table[W + 1][H + 1]:
        indices = t
    ans = table[W + 1][H + 1]

print(ans)
for i in indices:
    print(name[i])