def solve():
    dp = [[0]*w for _ in range(h)]
    dp[0][0] = 1
    for i in range(h):
        for j in range(w):
            if i==0==j or b[i][j]==0: continue
            if i: dp[i][j] += dp[i-1][j]
            if j: dp[i][j] += dp[i][j-1]
    return dp[-1][-1]

h,w,k,p = map(int,input().split())
h += 1; w += 1
name = []
pos = []
for _ in range(k):
    x,y,n = input().split()
    name.append(n)
    pos.append((int(x),int(y)))

b = [[1]*w for _ in range(h)]
ans = val = 0
for mask in range(1<<k):
    c = 0
    for i in range(k):
        x,y = pos[i]
        b[x][y] = mask>>i&1
        c += mask>>i&1
    if c > p: continue
    v = solve()
    if val < v:
        ans = mask
        val = v

print(val)
for i in range(k):
    if ans>>i&1: print(name[i])