using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Text;
using System.Text.RegularExpressions;
using System.Linq;

public class Program
{
    public static void Main(string[] args)
    {
        new Magatro().Solve();
    }
}

class Magatro
{
    private int H, W, K, P;
    private int[] x, y;
    private string[] N;

    private void Scan()
    {
        string[] line = Console.ReadLine().Split(' ');
        H = int.Parse(line[0]);
        W = int.Parse(line[1]);
        K = int.Parse(line[2]);
        P = int.Parse(line[3]);
        x = new int[K];
        y = new int[K];
        N = new string[K];
        for (int i = 0; i < K; i++)
        {
            line = Console.ReadLine().Split(' ');
            x[i] = int.Parse(line[0]);
            y[i] = int.Parse(line[1]);
            N[i] = line[2];
        }
    }

    public void Solve()
    {
        Scan();
        int max = -1;
        int ans = 0;

        for (int i = 0; i < (1 << K); i++)
        {
            if (BitCount(i) != P)
            {
                continue;
            }
            int cnt = Count(i);
            if (max < cnt)
            {
                ans = i;
                max = cnt;
            }
        }
        Console.WriteLine(max);

        for (int i = 0; i < K; i++)
        {
            int j = 1 << i;
            if ((ans & j) != 0)
            {
                Console.WriteLine(N[i]);
            }
        }
    }

    private int Count(int i)
    {
        var d = new Dictionary<Pair<int, int>, bool>();
        for (int j = 0; j < K; j++)
        {
            int k = 1 << j;
            if ((i & k) == 0)
            {
                d[new Pair<int, int>(x[j], y[j])] = true;
            }
        }
        var dp = new int[H + 1, W + 1];
        dp[0, 0] = 1;
        for (int j = 0; j <= H; j++)
        {
            for (int k = 0; k <= W; k++)
            {
                bool o;
                if (d.TryGetValue(new Pair<int, int>(j,k),out o)) continue;
                if (j < H)
                {
                    dp[j + 1, k] += dp[j, k];
                }
                if (k < W)
                {
                    dp[j, k + 1] += dp[j, k];
                }
            }
        }
        return dp[H, W];
    }

    private int BitCount(int n)
    {
        n = (n & 0x55555555) + (n >> 1 & 0x55555555);
        n = (n & 0x33333333) + (n >> 2 & 0x33333333);
        n = (n & 0x0f0f0f0f) + (n >> 4 & 0x0f0f0f0f);
        n = (n & 0x00ff00ff) + (n >> 8 & 0x00ff00ff);
        n = (n & 0x0000ffff) + (n >> 16 & 0x0000ffff);
        return n;
    }
}

struct Pair<F, S>
{
    public F First;
    public S Second;
    public Pair(F f, S s)
    {
        First = f;
        Second = s;
    }
}